1 SDM SERVICES https://sites.google.com/site/sdmservice15/ For quantities and units 1. When these numbers are multiplied, (6 × 103) (5 × 105), the result is A. 3 × 108 B. 30 × 108 C. 300 × 109 D. 3,000 × 107 Answer: Option B 2. Resistance is measured in A. henries B. ohms C. hertz D. watts Answer: Option B 3. The number 65,000 expressed in scientific notation as a number between 1 and 10 times a power of ten is A. 0.65 × 104 B. 6.5 × 104 C. 65 × 104 D. 650 × 103 Answer: Option B 4. When converting 7,000 nA to microamperes, the result is A. 0.007 µA B. 0.7 µA C. 700 µA D. 7 µA Answer: Option 5. The number of kilowatts in 135 milliwatts is A. 1.35 × 10–4 kW B. 135 × 10–3 kW C. 0.0135 kW D. 0.00135 kW Answer: Option A @SDM 2 6. SDM SERVICES https://sites.google.com/site/sdmservice15/ . The number 4.4 × 106 ohms expressed using a metric prefix is A. 4k B. 4.4 k C. 4M D. 4.4 M Answer: Option D 7. The number of microamperes in 2 milliamperes is A. 2 µA B. 20 µA C. 200 µA D. 2,000 µA Answer: Option D 8. The number of millivolts in 0.06 kilovolts is A. 600 V B. 6,000 mV C. 60,000 mV D. 600,000 mV Answer: Option C 9. Eighteen thousand watts is the same as A. 18 mW B. 18 MW C. 18 kW D. 18 µW Answer: Option C 10. The number 3.2 × 10–5 A expressed using a metric prefix is A. 32 µA B. 3.3 µA C. 320 mA @SDM 3 SDM SERVICES https://sites.google.com/site/sdmservice15/ D. 3,200 mA Answer: Option A 11. When converting 0.16 mA to microamperes, the result is A. 16 µA B. 160 µA C. 1,600 µA D. 0.0016 µA Answer: Option B 12. When these numbers are added, (87 × 105) + (2.5 × 106), the result is A. 1.12 × 104 B. 11.2 × 105 C. 112 × 105 D. 1,120 × 106 Answer: Option C 13. The quantity 3.3 × 103 is the same as A. 330 B. 3,300 C. 33,000 D. 0.0033 Answer: Option B 14. Which of the following is not an electrical quantity? A. voltage B. current C. distance D. power Answer: Option C 15. Seven thousand volts can be expressed as A. 7 kV @SDM 4 SDM SERVICES https://sites.google.com/site/sdmservice15/ B. 7 MV C. 7 mV D. either 7 kV or 7 mV Answer: Option A 16. The number 4,500,000 can be expressed as A. 4,500 × 106 B. 4.5 × 106 C. 4.5 × 10-3 D. either 4,500 × 104 or 4.5 × 106 Answer: Option B 17. When converting 1,600 kilohms to megohms, the result is A. 1,600,000 M B. 160 M C. 1.6 M D. 0.160 M Answer: Option C 18. What is (79 × 106)/(12 × 10–8)? A. 6,580 × 1012 B. 658 × 1010 C. 6.58 × 1014 D. 0.658 × 1016 Answer: Option C 19. Fourteen milliamperes can be expressed as A. 14 MA B. 14 µA C. 14 kA D. 14 mA Answer: Option D @SDM 5 SDM SERVICES https://sites.google.com/site/sdmservice15/ 20. The number 4.38 × 10–3 expressed as a number having a power of 10–6 is A. 4,380 × 10–6 B. 438 × 10–6 C. 43,800 × 10–6 D. 438,000 × 10–6 Answer: Option A . 21. Voltage is measured in A. volts B. farads C. watts D. ohms Answer: Option A 22. The number 0.0003 multiplied by 10-3 is A. 0.0000003 B. 0.0003 C. 3 D. 3,000 Answer: Option A 23. The number of megohms in 0.03 kilohms is A. 0.00002 M B. 0.0002 M C. 3 × 10–5 M D. either 0.00002 M or 0.0002 M Answer: Option C 24. The quantity 43 × 10-3 is the same as A. 0.043 B. 0.430 @SDM 6 SDM SERVICES https://sites.google.com/site/sdmservice15/ C. 430 D. 43,000 Answer: Option A 25. Current is measured in A. watts B. volts C. henries D. amperes Answer: Option D. Ohm's Law 1. An electric heater draws 3.5 A from a 110 V source. The resistance of the heating element is approximately A. 385 B. 38.5 C. 3.1 D. 31 Answer: Option D 2. If 750 µA is flowing through 11 k A. 8.25 V B. 82.5 V C. 14.6 V D. 146 V of resistance, what is the voltage drop across the resistor? Answer: Option A 3. The formula to find I when the values of V and R are known is A. I = VR B. I = R/V C. V = IR D. I = V/R Answer: Option D @SDM 7 4. SDM SERVICES https://sites.google.com/site/sdmservice15/ A resistor is connected across a 50 V source. What is the current in the resistor if the color code is red, orange, orange, silver? A. 2 mA B. 2.2 mA C. 214 mA D. 21.4 mA Answer: Option B 5. Approximately how many milliamperes of current flow through a circuit with a 40 V source and 6.8 k resistance? A. 27.2 mA B. 59 mA C. 5.9 mA D. 590 mA of Answer: Option C 6. How much resistance is required to limit the current from a 12 V battery to 3.6 mA? A. 3.3 k B. 33 k C. 2.2 k D. 22 k Answer: Option A 7. What is the voltage source for a circuit carrying 2 A of current through a 36 A. 1.8 V B. 18 V C. 7.2 V D. 72 V resistor? Answer: Option D 8. What is the approximate resistance setting of a rheostat in which 650 mA of current flows with a 150 V source? A. 9.7 B. 97 @SDM 8 SDM SERVICES https://sites.google.com/site/sdmservice15/ C. 23 D. 230 Answer: Option D 9. How much voltage is needed to produce 2.5 A of current through a 200 A. 50 V B. 500 V C. 80 V D. 8V resistor? Answer: Option B 10. When there is 12 mA of current through a 1.2 k A. 14.4 V B. 1.4 V C. 100 V D. 10 V resistor, the voltage across the resistor is Answer: Option A Explanation: V = IR (Ohms Law) = 12 X 10-3 X 1.2 X 10 3 = 12 X 1.2 = 14.4 V 11. A resistance of 3.3 M A. 15.1 µA B. 151 µA C. 66 mA D. 660 mA is connected across a 500 V source. The resulting current is approximately Answer: Option B 12. You are measuring the current in a circuit that is operated on an 18 V battery. The ammeter reads 40 mA. Later you notice the current has dropped to 20 mA. How much has the voltage changed? A. 9V B. 900 mV C. 0V @SDM 9 SDM SERVICES https://sites.google.com/site/sdmservice15/ D. 18 V Answer: Option A 13. The current through a flashlight bulb is 40 mA and the total battery voltage is 4.5 V. The resistance of the bulb is approximately A. 112 B. 11.2 C. 1.2 D. 18 Answer: Option A 14. If you wish to increase the amount of current in a resistor from 120 mA to 160 mA by changing the 24 V source, what should the new voltage setting be? A. 8V B. 320 V C. 3.2 V D. 32 V Answer: Option D 15. If 24 V are applied across a resistor and there are 10.9 mA of current, the resistance is A. 220 k B. 22 k C. 2.2 k D. 220 Answer: Option C 16. How much resistance is needed to draw 17.6 mA from a 12 volt source? A. 212 B. 6.8 k C. 68 D. 680 @SDM 10 SDM SERVICES https://sites.google.com/site/sdmservice15/ Answer: Option D 17. How much current is produced by a voltage of 18 kV across a 15 k A. 1.2 A B. 12 A C. 120 mA D. 12 mA resistance? Answer: Option A 18. A current of 200 µA through a 6.8 k A. 34.4 V B. 340 V C. 13.6 V D. 1.36 V resistor produces a voltage drop of Answer: Option D 19. Four amperes of current are measured through a 24 much voltage does the source produce? A. 960 V B. 9.6 V C. 96 V D. 8V resistor connected across a voltage source. How Answer: Option C 20. Twelve volts are applied across a resistor. A current of 3 mA is measured. What is the value of the resistor? A. 4 B. 400 C. 4k D. 4.4 Answer: Option C 21. When 12 V are applied across a 68 A. resistor, the current is 816 mA @SDM 11 SDM SERVICES https://sites.google.com/site/sdmservice15/ B. 17.6 mA C. 176 mA D. 8.16 mA Answer: Option C 22. Approximately how much current flows through a 3.3 M A. 9 B. 90 C. 900 D. 9000 resistor across a 30 V source? A A A A Answer: Option A 23. A 120 V lamp-dimming circuit is controlled by a rheostat and protected from excessive current by a 3 A fuse. To what minimum resistance value can the rheostat be set without blowing the fuse? Assume a lamp resistance of 20 ohms. A. 40 B. 4 C. 2 D. 20 Answer: Option D 24. What is the approximate filament resistance of a light bulb if it operates from a 110 V source and 0.6 A of current is flowing? A. 183 B. 18.3 C. 66 D. 6.6 Answer: Option A 25. What is the approximate resistance of a rheostat if the voltage source is 18 V and the current is 220 mA? A. 8.2 k B. 820 C. 8.2 @SDM 12 SDM SERVICES https://sites.google.com/site/sdmservice15/ D. 82 Answer: Option D Series Circuits 1. When a fourth resistor is connected in series with three resistors, the total resistance A. increases by one-fourth B. increases C. decreases D. remains the same Answer: Option B 2. A string of five series resistors is connected across a 6 V battery. Zero voltage is measured across all resistors except R3. The voltage across R3 is A. 0V B. 1.2 V C. 6V D. 0.6 V Answer: Option C 3. A series circuit consists of three resistors with values of 120 is A. less than 120 B. the average of the values C. 720 D. 120 , 270 , and 330 . The total resistance Answer: Option C 4. A certain series circuit consists of a 1/8 W resistor, a 1/4 W resistor, and a 1/2 W resistor. The total resistance is 1200 . If each resistor is operating in the circuit at its maximum power dissipation, total current flow is A. 27 mA B. 2.7 mA C. 19 mA D. 190 mA Answer: Option A Explanation: Total P = P1 + P2 + P3 = 7/8w. P = I2R. @SDM 13 SDM SERVICES https://sites.google.com/site/sdmservice15/ I = sqrt (P/R) Now, P = 7/8w, R = 1200 ohm. Therefore, I= sqrt ( (7/8)/1200 ) = 0.0270030862 = 27 mA. 5. Which of the following series combinations dissipates the most power when connected across a 120 V source? A. one 220 resistor B. two 220 resistors C. three 220 D. four 220 resistors resistors Answer: Option A 6. When one of three series resistors is removed from a circuit and the circuit is reconnected, the current A. increases B. increases by one-third C. decreases by one-third D. decreases by the amount of current through the removed resistor Answer: Option A 7. The total power in a certain circuit is 12 W. Each of the four equal-value series resistors making up the circuit dissipates A. 12 W B. 48 W C. 3W D. 8W Answer: Option C 8. The following resistors (one each) are connected in a series circuit: 470 , 680 The voltage source is 20 V. Current through the 680 resistor is approximately A. 60 mA B. 30 mA C. 6 mA D. 300 mA ,1k , and 1.2 k . Answer: Option C @SDM 14 9. SDM SERVICES https://sites.google.com/site/sdmservice15/ A series circuit consists of a 4.7 k voltage drop is , a 12 k , and a 2.2 k A. the 12 k B. the 2.2 k C. the 4.7 k D. impossible to determine from the given information resistor. The resistor that has the most Answer: Option A 10. All the voltage drops and the source voltage added together in a series circuit is equal to A. the total of the voltage drops B. the source voltage C. zero D. the total of the source voltage and the voltage drops Answer: Option C 11. Two resistors are in series: a 5.6 k resistor and a 4.7 k resistor is 10 V. The voltage across the 4.7 k resistor is A. 8.39 V B. 10 V C. 2.32 V D. 0V resistor. The voltage drop across the 5.6 k Answer: Option A 12. Three 680 A. 69 mA B. 230 mA C. 23 mA D. 690 mA resistors are connected in series with a 470 V source. Current in the circuit is Answer: Option B 13. There are five resistors in a given series circuit and each resistor has 6 V dropped across it. The source voltage A. is 6 V B. depends on the current flow C. depends on the resistor values @SDM 15 SDM SERVICES https://sites.google.com/site/sdmservice15/ D. is 30 V Answer: Option D 14. If a 6 V and a 9 V source are connected series aiding, the total voltage is A. 6V B. 9V C. 3V D. 15 V Answer: Option D 15. Five resistors are connected in a series and there is a current of 3 A into the first resistor. The amount of current into the second resistor is A. 3A B. 1A C. 4A D. 0.3 A Answer: Option A . 16. The total resistance of eight 5.6 k A. 8 B. 5,600 C. 4,480 D. 44,800 resistors in series is Answer: Option D 17. A series circuit has a 24 V source and a total resistance of 120 A. 24 mA B. 200 mA C. 120 mA D. 20 mA . The current through each resistor is Answer: Option B 18. To measure the current out of the second resistor in a circuit consisting of four resistors, an ammeter can be placed A. between the second and third resistors @SDM 16 SDM SERVICES https://sites.google.com/site/sdmservice15/ B. at the negative terminal of the source C. between the third and fourth resistors D. at any point in the circuit Answer: Option D 19. A 12 V battery is connected across a series combination of 68 of current is A. 326 mA B. 16.3 mA C. 32.6 mA D. 163 mA , 47 , 220 , and 33 . The amount Answer: Option C 20. If a 24 V and a 6 V battery are series opposing, the total voltage is A. 30 V B. 24 V C. 18 V D. 0V Answer: Option C 21. A series circuit consists of three resistors. Two resistors are 1.2 k The value of the third resistor A. is 9,600 B. is 960 C. is 1.2 k D. cannot be determined each. The total resistance is 12 k . Answer: Option A 22. Four equal-value resistors are in series with a 12 V battery and 13.63 mA are measured. The value of each resistor is A. 22 B. 220 C. 880 D. 88 @SDM 17 SDM SERVICES https://sites.google.com/site/sdmservice15/ Answer: Option B Explanation: Total Resistance, r = 12 / 13.63 = 0.880 in ohms Total Resistance, r= 880 Each resistance value = r/4 = 880/4 Each resistance value = 220 ohms . 23. Two 1.5 V cells are connected series opposing across two 100 A. 15 mA B. 5 mA C. 2 mA D. 0A resistors in series. Total current flow is Answer: Option D 24. The total resistance of a circuit is 680 . The percentage of the total voltage appearing across a 47 resistor that makes up part of the total series resistance is A. 68% B. 47% C. 69% D. 6.91% Answer: Option D 25. Two 6 V batteries are connected series aiding across two 1.2 k resistor is A. 5 mA B. 10 mA C. 0A D. 2.5 mA resistors in series. Current through each Answer: Option A Series-Parallel Circuits 1. The internal resistance of a 20,000 ohm/volt voltmeter set on its 5 V range is @SDM 18 SDM SERVICES https://sites.google.com/site/sdmservice15/ A. 20,000 B. 100,000 C. 200,000 D. 1,000,000 Answer: Option B 2. Two 1.2 k resistors are in series and this series combination is in parallel with a 3.3 k resistance is A. 138 B. 1,389 C. 5,700 D. 880 resistor. The total Answer: Option B 3. The output of a certain voltage divider is 12 V with no load. When a load is connected, the output voltage A. decreases B. increases C. remains the same D. becomes zero Answer: Option A 4. A certain voltage divider consists of two 12 k have the most effect on the output voltage? A. 1M B. 24 k C. 18 k D. 12 k resistors in series. Which of the following load resistors will Answer: Option D 5. A voltage divider consists of two 68 k A. 12 V B. 24 V C. 0V D. 6V resistors and a 24 V source. The unknown output voltage is @SDM 19 SDM SERVICES https://sites.google.com/site/sdmservice15/ Answer: Option A 6. Three 10 k resistors are connected in series. A 20 k resistor is connected in parallel across one of the 10 k resistors. The voltage source is 24 V. The total current in the circuit is A. 900 B. 9 mA C. 90 mA D. 800 A A Answer: Option A 7. A certain voltage divider consists of three 1 k have the least effect on the output voltage? A. 1M B. 100 k C. 1k D. 330 resistors in series. Which of the following load resistors will Answer: Option A 8. The parallel combination of a 470 resistor and a 1.5 k resistor is in series with the parallel combination of five 1 k resistors. The source voltage is 50 V. The percentage of the load current through any single 1 k resistor is A. 25% B. 20% C. 100% D. 50% Answer: Option B 9. A certain Wheatstone bridge has the following resistor values: R1 = 10 k The unknown resistance is A. 24 B. 2.4 C. 300 D. 3,000 , R2 = 720 , and R4 = 2.4 k Answer: Option D 10. On which of the following voltage range settings will a voltmeter present the minimum load on a circuit? @SDM . 20 SDM SERVICES https://sites.google.com/site/sdmservice15/ A. 1V B. 50 V C. 500 V D. 1,000 V Answer: Option D 11. The internal resistance of a 30,000 ohm/volt voltmeter set on its 50 V range is A. 15,000 B. 150,000 C. 1,500,000 D. 15,000,000 Answer: Option C 12. The parallel combination of a 6.8 k resistor and a 10 k resistor is in series with the parallel combination of a 2.2 k resistor and a 1 k resistor. A 100 V source is connected across the circuit. The resistor(s) with the greatest voltage drop is (are) A. 6.8 k B. 2.2 k C. 6.8 k and 10 k D. 2.2 k and 1 k Answer: Option C 13. When a load resistance is removed from the output of a voltage divider circuit, the current drawn from the source A. decreases B. increases C. remains the same D. is cut off Answer: Option A 14. A certain circuit is composed of two parallel resistors. The total resistance is 1,403 is 2 k . The other resistor value is A. 1,403 B. 4.7 k . One of the resistors @SDM 21 SDM SERVICES https://sites.google.com/site/sdmservice15/ C. 2k D. 3,403 Answer: Option B 15. The parallel combination of a 470 resistor and a 680 of four 2 k resistors. The total resistance is A. 1,650 B. 1,078 C. 77.8 D. 778 resistor is in series with the parallel combination Answer: Option D 16. A 12 k resistor, a 15 k resistor, and a 22 k resistor are in series with two 10 k resistors that are in parallel. The source voltage is 75 V. Current through the 15 k resistor is approximately A. 14 mA B. 1.4 mA C. 5 mA D. 50 mA Answer: Option B 17. A 6 V battery output is divided down to obtain two output voltages. Three 2.2 k provide the two taps. The two output voltages are A. 2 V, 4 V B. 2 V, 2 V C. 2 V, 6 V D. 4 V, 6 V resistors are used to Answer: Option A 18. Two 3.3 k resistors are in series and this series combination is in parallel with a 4.7 k resistor. The voltage across one of the 3.3 k resistors is 12 V. The voltage across the 4.7 k resistor is A. 24 V B. 12 V C. 0V D. 6V @SDM 22 SDM SERVICES https://sites.google.com/site/sdmservice15/ Answer: Option A 19. A balanced Wheatstone bridge consists of an R of 3,500 V value of RUNK is A. 680 B. 1,029 C. 200 D. 880 , an R2 of 200 , and an R3 of 680 . The Answer: Option B 20. In a certain five-step R/2R ladder network, the smallest resistor value is 1 k A. indeterminable B. 2k C. 10 k D. 20 k . The largest value is Answer: Option B 21. A voltage divider consists of two 100 k load resistor of 1 M A. 0.57 V B. 6V C. 12 V D. 5.7 V resistors and a 12 V source. What will the output voltage be if a is connected to the output? Answer: Option D 22. The parallel combination of a 470 resistor and a 1.2 k resistor is in series with the parallel combination of three 3 k resistors. A 200 V source is connected across the circuit. The resistor with the most current has a value of A. 470 B. 3k C. 470 D. 1.2 k or 1.2 k Answer: Option C Branch, Loop and Node Analyses @SDM 23 1. SDM SERVICES https://sites.google.com/site/sdmservice15/ Find the node voltage VA. A. 6V B. 12 V C. 4.25 V D. 3V Answer: Option C 2. What is the current through R2? A. 3.19 A B. 319 mA C. 1.73 A D. 173 mA Answer: Option D 3. Find branch current IR2. @SDM 24 SDM SERVICES https://sites.google.com/site/sdmservice15/ A. 5.4 mA B. –5.4 mA C. 113.0 mA D. 119.6 mA Answer: Option C 4. Find the node voltage VA. A. 518 mV B. 5.18 V C. 9.56 V D. 956 mV Answer: Option B 5. Find I2. 4I1 + 4I2 = 2 6I1 + 7I2 = 4 A. 1A B. –1 A C. 100 mA D. –100 mA Answer: Option A @SDM 25 6. SDM SERVICES https://sites.google.com/site/sdmservice15/ What is the voltage drop across R1? A. 850 mV B. 7.82 V C. 9.18 V D. 918 mV Answer: Option B 7. What is the voltage drop across R2? A. 3.5 V B. 4.18 V C. 1.5 V D. 145 mV Answer: Option B 8. In assigning the direction of branch currents, A. the directions are critical B. the directions are not critical C. they must point into a node D. they must point out of a node Answer: Option B 9. Find I1. 4I1 + 4I2 = 2 @SDM 26 SDM SERVICES https://sites.google.com/site/sdmservice15/ 6I1 + 7I2 = 4 A. 0.5 A B. 50 mA C. –0.5 A D. –50 mA Answer: Option C 10. Using the mesh current method, find the branch current, IR1, in the above figure. A. 115 mA B. 12.5 mA C. 12.5 A D. 135 mA Answer: Option A 11. What is the current through R2? A. 177 mA B. 250 mA C. 500 mA D. 125 mA Answer: Option A. @SDM 27 SDM SERVICES https://sites.google.com/site/sdmservice15/ 12. The first row of a certain determinant has the numbers 3 and 5. The second row has the numbers 7 and 2. The value of this determinant is A. 31 B. –31 C. 39 D. –29 Answer: Option D 13. The first row of a certain determinant has the numbers 10 and 6. The second row has the numbers 3 and 5. The value of this determinant is A. 18 B. 50 C. 32 D. –32 Answer: Option C 14. What is the voltage drop across R3? A. 112 mV B. 11.25 V C. 180 mV D. 1.80 V Answer: Option C @SDM 28 SDM SERVICES https://sites.google.com/site/sdmservice15/ 15. The expansion method for evaluating determinants is A. better than any other method B. good for only one determinant C. more flexible than the cofactor method D. good for second- and third-order determinants Answer: Option D 16. The branch current method uses A. Kirchhoff's voltage and current laws B. Thevenin's theorem and Ohm's law C. Kirchhoff's current law and Ohm's law D. the superposition theorem and Thevenin's theorem Answer: Option A Alternating Current and Voltage 1. If the rms voltage drop across a 15 k A. 15 mA B. 1.5 mA C. 10 mA D. 1 mA resistor is 16 V, the peak current through the resistor is Answer: Option B 2. The conductive loop on the rotor of a simple two-pole, single-phase generator rotates at a rate of 400 rps. The frequency of the induced output voltage is A. 40 Hz B. 100 Hz C. 400 Hz D. indeterminable Answer: Option C 3. How many degrees are there in A. 6° B. 60° C. 180° D. 27° /3 rad? @SDM 29 SDM SERVICES https://sites.google.com/site/sdmservice15/ Answer: Option B 4. To produce an 800 Hz sine wave, a four-pole generator must be operated at A. 200 rps B. 400 rps C. 800 rps D. 1,600 rps Answer: Option B 5. One sine wave has a positive-going zero crossing at 15° and another sine wave has a positive-going zero crossing at 55°. The phase angle between the two waveforms is A. 0° B. 45° C. 40° D. none of the above Answer: Option C 6. If the rms current through a 4.7 k A. 4V B. 18.8 V C. 26.6 V D. 2.66 V resistor is 4 mA, the peak voltage drop across the resistor is Answer: Option C 7. A pulse waveform has a high time of 8 ms and a pulse width of 32 ms. The duty cycle is A. 25% B. 50% C. 1% D. 100% Answer: Option A 8. A 20 kHz pulse waveform consists of pulses that are 15 A. is 1% B. is 30% C. is 100% s wide. The duty cycle @SDM 30 SDM SERVICES https://sites.google.com/site/sdmservice15/ D. cannot be determined Answer: Option B 9. If the peak of a sine wave is 13 V, the peak-to-peak value is A. 6.5 V B. 13 V C. 26 V D. none of the above Answer: Option C 10. A sinusoidal current has an rms value of 14 mA. The peak-to-peak value is A. 45.12 mA B. 16 mA C. 39.6 mA D. 22.6 mA Answer: Option C 11. A signal with a 400 A. 250 Hz B. 2,500 Hz C. 25,000 Hz D. 400 Hz s period has a frequency of Answer: Option B 12. A sine wave of 15 kHz is changing at a faster rate than a sine wave with a frequency of A. 25 kHz B. 12 kHz C. 18 kHz D. 1.3 MHz Answer: Option B 13. The average value of a 12 V peak sine wave over one complete cycle is A. 0V B. 1.27 V C. 7.64 V @SDM 31 SDM SERVICES https://sites.google.com/site/sdmservice15/ D. 6.37 V Answer: Option A 14. When a sine wave has a frequency of 100 Hz in 12 s it goes through A. 1/100 cycle B. 12 cycles C. 120 cycles D. 1,200 cycles Answer: Option D 15. A sawtooth wave has a period of 10 ms. Its frequency is A. 10 Hz B. 50 Hz C. 100 Hz D. 1,000 Hz Answer: Option C 16. Two series resistors are connected to an ac source. If there are 7.5 V rms across one resistor and 4.2 V rms across the other, the peak source voltage is A. 16.54 V B. 1.65 V C. 10.60 V D. 5.93 V Answer: Option A 17. If a sine wave goes through 10 cycles in 20 A. 20 B. 4 s C. 2 s D. 100 s, the period is s s Answer: Option C 18. A square wave has a period of 60 A. 5 kHz B. 50 kHz s. The first odd harmonic is @SDM 32 SDM SERVICES https://sites.google.com/site/sdmservice15/ C. 500 kHz D. 33.33 kHz Answer: Option B 19. Sine wave A has a positive-going zero crossing at 45°. Sine wave B has a positive-going zero crossing at 60°. Which of the following statements is true? A. Wave A leads wave B by 15°. B. Wave A lags wave B by 15°. C. Wave A leads wave B by 105°. D. Wave A lags wave B by 105°. Answer: Option A 20. A phasor represents A. the magnitude and a quantity direction B. the width of a quantity C. the phase angle D. the magnitude of a quantity Answer: Option A 21. A sine wave with a period of 4 ms is changing at a faster rate than a sine wave with a period of A. 0.0045 s B. 2 ms C. 1.5 ms D. 3,000 s Answer: Option A 22. A waveform has a baseline of 3 V, a duty cycle of 20%, and an amplitude of 8 V. The average voltage value is A. 4V B. 4.6 V C. 1.6 V D. 11 V Answer: Option A 23. A sine wave with an rms value of 12 V is riding on a dc level of 18 V. The maximum value of the resulting waveform is A. 6V @SDM 33 SDM SERVICES https://sites.google.com/site/sdmservice15/ B. 30 V C. 35 V D. 0V Answer: Option C 24. If the rms current through a 6.8 k A. 5.44 V B. 54.4 V C. 7.07 V D. 8V resistor is 8 mA, the rms voltage drop across the resistor is Answer: Option B 25. The average half-cycle value of a sine wave with a 40 V peak is A. 25.48 V B. 6.37 V C. 14.14 V D. 50.96 V Answer: Option A Inductors 1. An inductance of 0.08 A. 0.0000008 H B. 0.000000008 H C. 0.000008 H D. 0.00008 mH H is larger than Answer: Option B 2. A 240 H inductor is equivalent to a A. 0.240 mH inductor B. 0.000240 mH inductor C. 240 mH inductor D. 240 H inductor Answer: Option A 3. A 2 mH, a 3.3 mH, and a 0.2 mH inductor are connected in series. The total inductance is @SDM 34 SDM SERVICES https://sites.google.com/site/sdmservice15/ A. 55 mH B. less than 0.2 mH C. less than 5.5 mH D. 5.5 mH Answer: Option D 4. A 5 mH, a 4.3 mH, and a 0.6 mH inductor are connected in parallel. The total inductance is A. 9.9 mH B. greater than 5 mH C. 9.9 mH or greater than 5 mH D. less than 0.6 mH Answer: Option D 5. The voltage across a coil when di/dt = 20 mA/ A. 16 mV B. 160 mV C. 1.6 mV D. 2.5 mV s and L = 8 H is Answer: Option B 6. A sine wave voltage is applied across an inductor. When the frequency of the voltage is decreased, the current A. is increased B. is decreased C. does not change D. momentarily goes to zero Answer: Option A 7. Two 10 H inductors are in parallel and the parallel combination is in series with a third 10 H inductor. What is the approximate total reactance when a voltage with a frequency of 7 kHz is applied across the circuit terminals? A. 219 k B. 66 k C. 660 k @SDM 35 SDM SERVICES https://sites.google.com/site/sdmservice15/ D. 1.3 M Answer: Option C 8. An ohmmeter is connected across an inductor and the pointer indicates zero ohms. The inductor is A. good B. open C. shorted D. partly shorted Answer: Option C 9. Two inductors, L1 and L2, are in parallel. L1 has a value of 25 combination is in series with L3, a 20 300 kHz. The total rms current is A. 87 mA B. 870 mA C. 87 A D. 337 mA H and L2 a value of 50 H. The parallel H coil. The entire combination is across an ac source of 60 Vrms at Answer: Option B 10. An inductor, a 1 k resistor, and a switch are connected in series across a 6 V battery. At the instant the switch is closed, the inductor voltage is A. 0V B. 6V C. 12 V D. 4V Answer: Option B 11. The winding resistance of a coil can be increased by A. increasing the number of turns B. using a thinner wire C. changing the core material D. increasing the number of turns or using thinner wire Answer: Option D 12. An inductance of 0.43 mH is smaller than A. 43 H @SDM 36 SDM SERVICES https://sites.google.com/site/sdmservice15/ B. 430 C. 0.05 H D. 0.00043 H H Answer: Option C 13. An inductor and a resistor are in series with a sine wave voltage source. The frequency is set so that the inductive reactance is equal to the resistance. If the frequency is increased, then A. VR ≥ VL B. VL < VR C. VL = VR D. VL > VR Answer: Option D 14. The current through a 120 mH coil is changing at a rate of 150 mA/s. The voltage induced across the coil is A. 1.8 mV B. 18 mV C. 180 mV D. 1.25 mV Answer: Option B 15. When the current through an inductor decreases, the amount of energy stored in the electromagnetic field A. increases B. decreases C. remains the same D. doubles Answer: Option B 16. Three 15 mH inductors are in series. The total inductance is A. 15 mH B. 30 mH C. 45 mH D. 5 mH Answer: Option C 17. An 18 V power supply is connected across a coil with a winding resistance of 180 coil is . Current flow in the @SDM 37 SDM SERVICES https://sites.google.com/site/sdmservice15/ A. 1 mA B. 10 mA C. 100 mA D. 1A Answer: Option C 18. A switch, a 220 resistor, and a 60 mH inductor are in series across a 20 V battery. What is the current through the inductor two time constants after the switch is closed? A. 91 mA B. 78 mA C. 57 mA D. 400 mA Answer: Option B 19. A 320 value? H coil is in series with a 3.3 k A. 0.48 s B. 0.48 ms C. 0.48 D. 48 s resistor. How long does it take for current to build up to its full s Answer: Option C 20. Five inductors are connected in series. The lowest value is 8 μH. If the value of each inductor is twice that of the preceding one, and if the inductors are connected in order of ascending values, the total inductance is A. 8H B. 32 μH C. 64 μH D. 248 μH Answer: Option D 21. The inductance of an iron-core coil decreases if A. the number of turns is decreased B. the iron core is removed C. the length of the coil decreases D. none of the above Answer: Option A @SDM 38 22. SDM SERVICES https://sites.google.com/site/sdmservice15/ The following coils are in parallel: 75 approximately A. 6.9 H B. 14 H C. 2.2 H D. 155 H H, 40 H, 25 H, and 15 H. The total inductance is Answer: Option A 23. When the current through an inductor is cut in half, the amount of energy stored in the electromagnetic field A. is quartered B. quadruples C. doubles D. does not change Answer: Option A RC Circuits 1. In the complex plane, the number 14 – j5 is located in the A. first quadrant B. second quadrant C. third quadrant D. fourth quadrant Answer: Option D 2. Point +4 on the complex plane is A. 4 units above the origin on the j axis B. 4 units below the origin on the j axis C. 4 units right of the origin on the real axis D. 4 units left of the origin on the real axis Answer: Option C 3. A 470 resistor and a 0.2 rectangular form, is F capacitor are in parallel across a 2.5 kHz ac source. The admittance, Y, in @SDM 39 SDM SERVICES https://sites.google.com/site/sdmservice15/ A. 212 B. 2.12 mS + j3.14 mS C. 3.14 mS + j2.12 mS D. 318.3 Answer: Option B 4. A positive angle of 30° is equivalent to a negative angle of A. –30° B. –330° C. –60° D. –180° Answer: Option B 5. In a series RC circuit, 12 V(rms) is measured across the resistor and 15 V(rms) is measured across the capacitor. The rms source voltage is A. 3V B. 27 V C. 19.2 V D. 1.9 V Answer: Option C 6. A 6 kHz sinusoidal voltage is applied to a series RC circuit. The frequency of the voltage across the resistor is A. 0 Hz B. 12 kHz C. 6 kHz D. 18 kHz Answer: Option C 7. The voltages in Problem 4 are measured at a certain frequency. To make the capacitor voltage greater than the resistor voltage, the frequency A. must be increased B. must be decreased C. is held constant D. has no effect Answer: Option B @SDM 40 8. SDM SERVICES https://sites.google.com/site/sdmservice15/ In the complex plane, the number 4 + j3 is located in the A. first quadrant B. second quadrant C. third quadrant D. fourth quadrant Answer: Option A 9. When the frequency of the source voltage decreases, the impedance of a parallel RC circuit A. increases B. decreases C. does not change D. decreases to zero Answer: Option A 10. A 47 resistor and a capacitor with a capacitive reactance of 120 What is the circuit impedance, Z? A. 129 B. 12.9 C. 167 D. 73 are in series across an ac source. Answer: Option A 11. What is the value of the hypotenuse of a right triangle whose sides are 12 and 18? A. 4.24 B. 3.46 C. 2.16 D. 21.63 Answer: Option D 12. The complex number 6 + j6 is equivalent to A. 6 B. 36 C. 8.48 45° 45° 45° @SDM 41 SDM SERVICES https://sites.google.com/site/sdmservice15/ D. 8.48 90° Answer: Option C 13. In a parallel RC circuit, there is 100 mA through the resistive branch and 100 mA through the capacitive branch. The total rms current is A. 200 mA B. 100 mA C. 282 mA D. 141 mA Answer: Option D 14. An ac circuit consists of a resistor and a capacitor. To increase the phase angle above 45°, the following condition must exist: A. R = XC B. R > XC C. R < XC D. R = 5XC Answer: Option C 15. What is the angular difference between +j4 and –j4? A. 30° B. 90° C. 180° D. 270° Answer: Option C 16. A resistor and a capacitor are in series across a 20 V ac source. Circuit impedance is 4.33 k in the circuit is A. 9.2 mA B. 92 mA C. 4.6 mA D. 460 mA . Current flow Answer: Option C 17. For a certain load, the true power is 150 W and the reactive power is 125 VAR. The apparent power is A. 19.52 W B. 195.2 W @SDM 42 SDM SERVICES https://sites.google.com/site/sdmservice15/ C. 275 W D. 25 W Answer: Option B 18. When the frequency of the voltage applied to a series RC circuit is increased, the phase angle A. increases B. decreases C. remains the same D. becomes erratic Answer: Option B 19. In a series RC circuit, when the frequency and the resistance are halved, the impedance A. doubles B. is halved C. is reduced to one-fourth D. cannot be determined without values Answer: Option D 20. A2k resistor is in series with a 0.015 F capacitor across a 15 kHz ac source. What is the magnitude of the total impedance and the phase angle? A. 73.4 and θ = –19.5° B. 707 and θ = –19.5° C. 2121 D. 734 and θ = –19.5° and θ = –38.9° Answer: Option C Explanation: Xc = 1/2πfC = 707 Ω Z = R - jXc = 2000 - j(707) |z| = sqrt(R*R + Xc*Xc) = 2121 Ω Phase angle = arctangent(Xc/R) = 19.5° 21. A 12 k resistor is in series with a 0.02 F capacitor across a 1.2 kHz ac source. If the current is expressed in polar form as I = 0.3 0° mA, what is the source voltage expressed in polar form? A. 45.6 V B. 411.3 V @SDM 43 SDM SERVICES https://sites.google.com/site/sdmservice15/ C. 0.411 V D. 4.11 V Answer: Option D 22. The complex number 40 A. 55 + j55 B. 40 + j40 C. 45.88 + j65.52 D. 22.94 + j32.76 55° is equivalent to Answer: Option D 23. A 120 resistor is in parallel with a capacitor with a capacitive reactance of 40 across a 12 V ac source. What is the magnitude of the total impedance? A. 37.9 B. 3.7 C. 14,400 D. 4,800 . Both components are Answer: Option A 24. A 47 resistor and a capacitor with 150 of capacitive reactance are in series across an ac source. The impedance, expressed in rectangular form, is A. Z = 47 + j150 B. Z = 47 – j150 C. Z = 197 D. Z = 103 Answer: Option B 25. A2k resistor and a 0.002 mA. The true power is A. 84.5 mW B. 845 mW C. 13 mW D. 130 mW F capacitor are in series across an ac source. Current in the circuit is 6.50 Answer: Option A 26. A capacitor with 150 of capacitive reactance is across an ac source. The impedance, expressed in polar @SDM 44 SDM SERVICES https://sites.google.com/site/sdmservice15/ form, is A. Z = 150 B. Z = 150 90° C. Z = 150 –90° D. Z = 150 180° Answer: Option C 27. When the frequency of the voltage applied to a series RC circuit is decreased, the impedance A. increases B. decreases C. remains the same D. doubles Answer: Option A RLC Circuits and Resonance 1. A 10 resistor, a 90 mH coil, and a 0.015 impedance magnitude at 1,200 Hz below fr is A. 1,616 B. 161 C. 3,387 D. 1,771 F capacitor are in series across an ac source. The Answer: Option A 2. In a series RLC circuit that is operating above the resonant frequency, the current A. lags the applied voltage B. leads the applied voltage C. is in phase with the applied voltage D. is zero Answer: Option A 3. A 15 resistor, a 220 bandwidth of the circuit? A. H coil, and a 60 pF capacitor are in series across an ac source. What is the 138 MHz @SDM 45 SDM SERVICES https://sites.google.com/site/sdmservice15/ B. 10,866 Hz C. 1,907 Hz D. 138 kHz Answer: Option B 4. A resistor of 3 k , a 0.05 F capacitor, and a 120 mH coil are in series across a 5 kHz, 20 V ac source. What is the impedance, expressed in polar form? A. 636 B. 3,769 C. 433 D. 4,337 Answer: Option D 5. A 12 resistor, a 40 frequency is A. 28.1 Hz B. 281 Hz C. 2,810 Hz D. 10 kHz F capacitor, and an 8 mH coil are in series across an ac source. The resonant Answer: Option B 6. The impedance at the resonant frequency of a series RLC circuit with L = 20 mH, C = 0.02 90 is A. 0 B. 90 C. 20 k D. 40 k F, and RW = Answer: Option B 7. A 6.8 k resistor, a 7 mH coil, and a 0.02 F capacitor are in parallel across a 17 kHz ac source. The coil's internal resistance, RW, is 30 . The equivalent parallel resistance, Rp(eq), is A. 1,878 B. 18,780 C. 18,750 @SDM 46 SDM SERVICES https://sites.google.com/site/sdmservice15/ D. 626 Answer: Option B 8. Referring to Problem 20, what is the total parallel resistance (Rp(tot))? A. 4.99 B. 499 C. 4,992 D. 6,800 Answer: Option C 9. A 200 resistor, a coil with 30 of reactance, and a capacitor of unknown reactance are in series across an ac source. The circuit is at resonance. Circuit impedance A. is 230 B. is 170 C. is 200 D. cannot be determined Answer: Option C 10. Referring to Problem 8, the total current is 1. A. 1.5 A B. 573 mA If the resistance in parallel with a parallel resonant circuit is reduced, the bandwidth @SDM 47 SDM SERVICES https://sites.google.com/site/sdmservice15/ C. 5.73 A D. 1.19 A Answer: Option C A. disappears B. becomes sharper C. increases D. decreases Answer: Option D 12. A 90 resistor, a coil with 30 of reactance, and a capacitor with 50 across a 12 V ac source. The current through the resistor is A. 9 mA B. 90 mA C. 13 mA D. 130 mA of reactance are in series Answer: Option D 13. A resonant circuit has a lower critical frequency of 7 kHz and an upper critical frequency of 13 kHz. The bandwidth of the circuit is A. 7 kHz B. 13 kHz C. 20 kHz D. 4 kHz Answer: Option D 14. If the value of C in a series RLC circuit is decreased, the resonant frequency A. is not affected B. increases C. is reduced to zero D. decreases Answer: Option B 15. A 24 resistor, an inductor with a reactance of 120 , and a capacitor with a reactance of 120 series across a 60 V source. The circuit is at resonance. The voltage across the inductor is A. are in 60 V @SDM 48 SDM SERVICES https://sites.google.com/site/sdmservice15/ B. 660 V C. 30 V D. 300 V Answer: Option D 16. To tune a parallel resonant circuit to a higher frequency, the capacitance should be A. increased B. decreased C. left alone D. replaced with inductance Answer: Option B 17. In a certain series resonant circuit, VC = 125 V, VL = 125 V, and VR = 40 V. The value of the source voltage is A. 125 V B. 250 V C. 290 V D. 40 V Answer: Option D 18. A certain series resonant circuit has a bandwidth of 2 kHz. If the existing coil is replaced with one having a higher value of Q, the bandwidth will A. increase B. remain the same C. decrease D. be less selective Answer: Option C 19. A 9 mH coil is in parallel with a 0.015 F capacitor across an 18 kHz ac source. The coil's internal resistance, RW, is 60 . The circuit impedance is A. 17,340 B. 1,734 C. 290 D. 1,018 Answer: Option A 20. A 15 resistor, an inductor with 8 inductive reactance, and a capacitor with 12 reactance are in parallel across an ac voltage source. The circuit impedance is capacitive @SDM 49 SDM SERVICES https://sites.google.com/site/sdmservice15/ A. 12.7 B. 127 C. 4,436 D. 6,174 Answer: Option A A certain series RLC circuit with a 200 Hz, 15 V ac source has the following values: R = 12 F, and L = 10 mH. The total impedance, expressed in polar form, is A. 12.28 12.34° B. 12.57 12.34° C. 9.95 D. 12.62 , C = 80 12.34° 12.34° Answer: Option A Circuit Theorems in AC Analysis 1. Determine V when R is 180 TH 1 A. 135 63.4° V B. 13.5 63.4° V C. 12.2 0° V D. 122 0° V and XL is 90 . Answer: Option B 2. For the given circuit, find VTH for the circuit external to RL. A. 4.69 51.3° V @SDM 50 SDM SERVICES https://sites.google.com/site/sdmservice15/ B. 4.69 38.7° V C. 469 38.7° mV D. 6 0° V Answer: Option B 3. Referring to the given circuit, find ZTH if R is 15 k A. 89.82 B. 19.2 –38.3° k C. 9.38 –51.3° k D. 180 –38.3° k and RL is 38 k . –51.3° k Answer: Option C 4. For the circuit shown, determine ZTH for the portion of the circuit external to RL. A. 66.7 –33.7° k B. 6.67 –333.7° k C. 14.4 –56.3° k D. 1.44 –33.7° k Answer: Option B @SDM 51 5. SDM SERVICES https://sites.google.com/site/sdmservice15/ Referring to the given circuit, what is ZTH if R1 is changed to 220 A. 225 12.1° B. 225 77.9° C. 46 77.9° D. 46 12.1° ? Answer: Option C 6. Determine VTH for the circuit external to RL in the given figure. A. 135 63.4° V B. 13.5 63.4° V C. 13.5 0° V D. 135 0° V Answer: Option B 7. Referring to the given figure, determine ZTH as seen by RL if R1 is changed to 3.3 k . @SDM 52 SDM SERVICES https://sites.google.com/site/sdmservice15/ A. 1488 –70.7° B. 3859 –31.2° C. 5180 –50.5° D. 1828 –50.2° Answer: Option D 8. The two basic components of a Thevenin equivalent ac circuit are A. the equivalent voltage source and the equivalent series impedance B. the equivalent voltage source and the equivalent series resistance C. the equivalent voltage source and the equivalent parallel impedance D. the equivalent voltage source and the equivalent parallel resistance Answer: Option A 9. Referring to the given circuit, find ZTH if VS is 18 A. 9.82 –51.3° k B. 9.38 –51.3° k 0° V. @SDM 53 SDM SERVICES https://sites.google.com/site/sdmservice15/ C. 180 –38.3° k D. 19.2 –38.3° k Answer: Option B 10. In applying the superposition theorem, A. the sources are considered one at a time with all others replaced by their internal impedance B. all sources are considered independently C. all sources are considered simultaneously D. the sources are considered one at a time with all others replaced by their internal resistance Answer: Option A 11. If two currents are in the same direction at any instant of time in a given branch of a circuit, the net current at that instant A. is zero B. is the sum of the two currents C. is the difference between the two currents D. cannot be determined Answer: Option B 12. The Thevenin equivalent voltage is A. equal to the source voltage B. the same as the load voltage C. the open circuit voltage D. none of the above Answer: Option C 13. Referring to the given circuit, L A. must be in parallel with RL B. must be placed in parallel with VS C. must have a reactance equal to XC D. has no effect on the result Answer: Option D @SDM 54 SDM SERVICES https://sites.google.com/site/sdmservice15/ 14. Referring to the given circuit, find ZTH for the part of the circuit that is external to RL. A. 129 21.4° B. 43.7 68.6° C. 43.7 21.4° D. 12.9 68.6° Answer: Option B 15. In order to get maximum power transfer from a capacitive source, the load must A. have a capacitive reactance equal to circuit resistance B. have an impedance that is the complex conjugate of the source impedance C. be as capacitive as it is inductive D. none of the above Answer: Option B 16. Referring to the given circuit, determine ZTH as seen by RL. A. 1444 –48.5° @SDM 55 SDM SERVICES https://sites.google.com/site/sdmservice15/ B. 4176 C. 956 D. 1444 –73.3° –48.5° –73.3° Answer: Option A 17. Referring to the given circuit, how much power, in watts, is delivered to the speaker at the determined frequency if VS = 4.5 VRMS? A. 226 mW B. 2.26 mW C. 4.24 mW D. 424 mW Answer: Option D 18. The Norton equivalent current is @SDM 56 SDM SERVICES https://sites.google.com/site/sdmservice15/ A. the current through the load B. the open-current from the source C. the short circuit current D. none of the above Answer: Option C 19. Determine V if R is changed to 3.3 k TH 1 A. 0.574 B. 4.63 16.7° V C. 4.63 39.5° V D. 0.463 . 16.7° V 39.5° V Answer: Option C 20. Referring to the given circuit, what is VTH if VS = 12 A. 4.69 38.7° V B. 9.38 38.7° V C. 12 0° V? 0° V @SDM 57 SDM SERVICES https://sites.google.com/site/sdmservice15/ D. 6 0° V Answer: Option B 21. For the circuit given, determine the Thevenin voltage as seen by RL. A. 0.574 B. 5.74 C. 0.574 D. 5.74 16.7° V 16.7° V –16.7° V –16.7° V Answer: Option D 22. Determine the frequency at which the maximum power is transferred from the amplifier to the speaker in the given figure. @SDM 58 SDM SERVICES https://sites.google.com/site/sdmservice15/ A. 1,027 Hz B. 10,270 Hz C. 6,330 Hz D. 63,330 Hz Answer: Option A 23. Norton's theorem gives A. an equivalent current source in parallel with an equivalent impedance B. an equivalent current source in series with an equivalent impedance C. an equivalent voltage source in parallel with an equivalent impedance D. an equivalent voltage source in series with an equivalent impedance Answer: Option A Three-Phase Systems in Power Applications 1. In a three-phase system, the voltages are separated by A. 45° B. 90° C. 120° @SDM 59 SDM SERVICES https://sites.google.com/site/sdmservice15/ D. 180° Answer: Option C 2. In a three-phase system, when the loads are perfectly balanced, the neutral current is A. zero B. one-third of maximum C. two-thirds of maximum D. at maximum Answer: Option A 3. In a -connected source driving a -connected load, the A. load voltage and line voltage are one-third the source voltage for a given phase B. load voltage and line voltage are two-thirds the source voltage for a given phase C. load voltage and line voltage cancel for a given phase D. load voltage, line voltage, and source phase voltage are all equal for a given phase Answer: Option D 4. In a certain three-wire Y-connected generator, the phase voltages are 2 kV. The magnitudes of the line voltages are A. 2,000 V B. 6,000 V C. 666 V D. 3,464 V Answer: Option D 5. In a -connected source feeding a Y-connected load, A. each phase voltage equals the difference of the corresponding load voltages B. each phase voltage equals the corresponding load voltage C. each phase voltage is one-third the corresponding load voltage D. each phase voltage is 60° out of phase with the corresponding load voltage Answer: Option A 6. In a Y-Y source/load configuration, the A. phase current, the line current, and the load current are all equal in each phase B. phase current, the line current, and the load current are 120° out of phase C. phase current and the line current are in phase, and both are 120° out of phase with the load current @SDM 60 SDM SERVICES https://sites.google.com/site/sdmservice15/ D. line current and the load current are in phase, and both are out of phase with the phase current Answer: Option A 7. In a Y-connected circuit, the magnitude of each line current is A. one-third the phase current B. three times the corresponding phase current C. equal to the corresponding phase current D. zero Answer: Option C 8. A constant load power means a uniform conversion of A. mechanical to electrical energy B. electrical to mechanical energy C. current to voltage D. voltage to current Answer: Option B 9. A two-phase generator is connected to two 90 load resistors. Each coil generates 120 V ac. A common neutral line exists. How much current flows through the common neutral line? A. 1.33 A B. 1.88 A C. 2.66 A D. 1.77 A Answer: Option D 10. A single-phase sinusoidal voltage of 120 V is connected to a 90 A. 13.3 mA B. 133 mA C. 1.33 A D. 6.2 A load. Current in the circuit is Answer: Option C 11. A three-phase generator is connected to three 90 load resistors. Each coil generates 120 V ac. A common neutral line exists. How much current flows through the common neutral line? A. 0A B. 1.33 A @SDM 61 SDM SERVICES https://sites.google.com/site/sdmservice15/ C. 3.99 A D. 2.66 A Answer: Option A 12. Compare the total copper cross sections in terms of current-carrying capacity for a single-phase and a three-phase 120 V system with effective load resistance of 15 . A. single-phase 32 A; three-phase 16 A B. single-phase 16 A; three-phase 8 A C. single-phase 8 A; three-phase 4 A D. single-phase 16 A; three-phase 0 A Answer: Option B 13. If in a Y-connected ac generator, each phase voltage has a magnitude of 90 VRMS, what is the magnitude of each line voltage? A. 0V B. 90 V C. 156 V D. 180 V Answer: Option C 14. Polyphase generators produce simultaneous multiple sinusoidal voltages that are separated by A. certain constant phase angles B. certain constant frequencies C. certain constant voltages D. certain constant currents Answer: Option A 15. In a balanced three-phase load, each phase has A. an equal amount of power 16. In a certain Y-Y system, the source phase currents each have a magnitude of 9 A. The magnitude of each load current for a balanced load condition is @SDM 62 SDM SERVICES https://sites.google.com/site/sdmservice15/ B. one-third of total power C. two-thirds of total power D. a power consumption equal to IL Answer: Option A A. 3A B. 6A C. 9A D. 27 A Answer: Option C 17. A three-phase -connected generator is driving a balanced load such that each phase current is 12 A in magnitude. When I θa = 12 30° A, what are the polar expressions for the other phase currents? A. I θb = 12 150° A, I θc = 12 –90° A B. I θb = 12 120° A, I θc = 12 30° A C. I θb = 12 30° A, I θc = 12 120° A D. I θb = 12 90° A, I θc = 12 90° A Answer: Option A 18. In a Y-connected circuit, between each line voltage and the nearest phase voltage, there is a phase angle of A. 0° B. 30° C. 60° D. 120° Answer: Option B 19. The most common type of ac motor is the A. single-phase induction motor B. two-phase induction motor C. three-phase induction motor D. two-phase squirrel-cage motor Answer: Option C 20. In a Y-connected source feeding a -connected load, @SDM 63 SDM SERVICES https://sites.google.com/site/sdmservice15/ A. each phase of the load has one-third of the full line voltage across it B. each phase of the load has two-thirds of the full line voltage across it C. each phase of the load has the full line voltage across it D. each phase of the load has a voltage across it equal to Answer: Option C 21. In a -connected generator, all of the phase voltages are A. zero B. equal in magnitude C. one-third of total D. one-sixth of total Answer: Option B Voltage, Current and Resistance 1. Materials with lots of free electrons are called A. conductors B. insulators C. semiconductors D. filters Answer: Option A 2. The unit of electrical charge is the A. coulomb B. joule C. volt D. watt Answer: Option A 3. Current flows in a circuit when A. a switch is opened B. a switch is closed C. the switch is either open or closed @SDM 64 SDM SERVICES https://sites.google.com/site/sdmservice15/ D. there is no voltage Answer: Option B 4. The minimum resistance value for a blue, gray, red, silver resistor is A. 612 B. 6,120 C. 6,800 D. 6,460 Answer: Option B Explanation: Because of 10% tolerance(last color silver), this resistance may vary 10% of 6800. Minimum resistance value = 6800 - 680 = 6120 Maximum resistance value = 6800 + 680 = 7480 View Answer Discuss in Forum Workspace Report 5. The maximum resistance value for a brown, red, yellow, gold resistor is A. 126,000 B. 126,600 C. 114,000 D. 132,000 Answer: Option A 6. Which of the following is not a type of energy source? A. generator B. rheostat C. solar cell D. battery Answer: Option B 7. When placed close together, two positively charged materials will A. attract B. become neutral C. become negative D. repel Answer: Option D @SDM 65 8. SDM SERVICES https://sites.google.com/site/sdmservice15/ The conductance of an 8 ohm resistance is A. 12.5 mS B. 8 mS C. 12 S D. 125 mS Answer: Option D 9. Electrons in the outer orbit are called A. nuclei B. valences C. waves D. shells Answer: Option B 10. A thermistor is a type of A. switch B. resistor C. battery D. power supply Answer: Option B 11. A two-terminal variable resistor is known as a A. potentiometer B. thermistor C. rheostat D. wiper Answer: Option C 12. Eight-tenths coulomb passes a point in 4 s. The current in amperes is A. 1.6 A B. 16 A C. 2A D. 0.2 A Answer: Option D 13. When the current is 2.5 A, how many coulombs pass a point in 0.2 s? @SDM 66 SDM SERVICES https://sites.google.com/site/sdmservice15/ A. 12.5 C B. 1.25 C C. 0.5 C D. 5C Answer: Option C 14. The colored bands for a 4,700 ohm resistor with a ten percent tolerance are A. yellow, violet, red, gold B. yellow, violet, orange, gold C. yellow, violet, red, silver D. orange, violet, red, silver Answer: Option C 15. A material that does not allow current under normal conditions is a(n) A. insulator B. conductor C. semiconductor D. valence Answer: Option A 16. The unit of electrical charge is the A. volt B. ampere C. joule D. coulomb Answer: Option D 17. A multimeter measures A. current B. voltage C. resistance D. current, voltage, and resistance Answer: Option D 18. If there is 6 A of current through the filament of a lamp, how many coulombs of charge move through the filament in 1.75 s? @SDM 67 SDM SERVICES https://sites.google.com/site/sdmservice15/ A. 10.5 C B. 105 C C. 3.4 C D. 34 C Answer: Option A 19. A wiper is the sliding contact in a A. switch B. photoconductive cell C. thermistor D. potentiometer Answer: Option D 20. A neutral atom with an atomic number of five has how many electrons? A. 1 B. 5 C. none D. depends on the type of atom Answer: Option B 21. A circuit breaker is a A. fuse B. switch C. resettable protective device D. resistor Answer: Option C 22. An ammeter is an electrical instrument used to measure A. current B. voltage C. resistance D. none of the above Answer: Option A 23. A red, red, orange, gold resistor has a nominal value of A. 22,000 @SDM 68 SDM SERVICES https://sites.google.com/site/sdmservice15/ B. 2,200 C. 22 D. 2.2 Answer: Option A 24. An ohmmeter is an instrument for measuring A. current B. voltage C. resistance D. wattage Answer: Option C 25. The current in a given circuit is not to exceed 24 A. Which value of fuse is best? A. a fuse is not necessary B. 10 A C. 24 A D. 20 A Answer: Option C Energy and Power 1. A 33 half-watt resistor and a 330 Which one(s) will overheat? A. 33 B. 330 C. both resistors D. neither resistor half-watt resistor are connected across a 12 V source. Answer: Option D 2. When the pointer of an analog ohmmeter reads close to zero, the resistor being measured is A. overheated B. shorted C. open D. reversed Answer: Option B 3. In 0.025 W, there are @SDM 69 SDM SERVICES https://sites.google.com/site/sdmservice15/ A. 25 kW B. 0.00025 mW C. 2,500 µW D. 25 mW Answer: Option D 4. A certain appliance uses 350 W. If it is allowed to run continuously for 24 days, how many kilowatt-hours of energy does it consume? A. 20.16 kWh B. 201.6 kWh C. 2.01 kWh D. 8.4 kWh Answer: Option B 5. A power supply produces a 0.6 W output with an input of 0.7 W. Its percentage of efficiency is A. 8.57% B. 42.85% C. 4.28% D. 85.7% Answer: Option D 6. A given power supply is capable of providing 6 A for 3.5 h. Its ampere-hour rating is A. 0.58 Ah B. 2.1 Ah C. 21 Ah D. 58 Ah Answer: Option C 7. A 15 V source is connected across a 12 A. 938 Wh B. 0.938 Wh C. 56.25 Wh D. 5.6 Wh resistor. How much energy is used in three minutes? Answer: Option B @SDM 70 SDM SERVICES https://sites.google.com/site/sdmservice15/ 8. At the end of a 14 day period, your utility bill shows that you have used 18 kWh. What is your average daily power? A. 1.286 kWh B. 12.85 kWh C. 535 kWh D. 252 kWh Answer: Option A 9. A 120 resistor must carry a maximum current of 25 mA. Its rating should be at least A. 4.8 W B. 150 mW C. 15 mW D. 480 mW Answer: Option B 10. If you used 400 W of power for 30 h, you have used A. 1.3 kWh B. 13.3 kWh C. 1.2 kWh D. 12 kWh Answer: Option D 11. A 6 V battery is connected to a 300 can it supply current to the load? A. 1h B. 200 h C. 2,000 h D. 10 h load. Under these conditions, it is rated at 40 Ah. How long Answer: Option C 12. In 40 kW, there are A. 0.4 mW B. 40,000 W C. 400 W D. 5,000 W Answer: Option B @SDM 71 SDM SERVICES https://sites.google.com/site/sdmservice15/ 13. If you used 600 W of power for 60 h, you have used A. 36 kWh B. 3.6 kWh C. 10 kWh D. 1 kWh Answer: Option A 14. If it takes 400 ms to use 12,000 J of energy, the power is A. 30 kW B. 30 W C. 3W D. 300 kW Answer: Option A 15. How many watt-hours represent 65 W used for 18 h? A. 11.7 Wh B. 1,170 Wh C. 11,700 Wh D. 117,000 Wh Answer: Option B 16. For 12 V and 40 mA, the power is A. 480 mW B. 0.480 W C. 480,000 µW D. all of the above Answer: Option D 17. A 220 resistor dissipates 3 W. The voltage is A. 73.3 V B. 2.5 V C. 25.7 V D. 257 V Answer: Option C @SDM 72 SDM SERVICES https://sites.google.com/site/sdmservice15/ 18. A 3.3 k resistor dissipates 0.25 W. The current is A. 8.7 mA B. 87 mA C. 8.7 µA D. 8.7 A Answer: Option A Explanation: W = I2R I = square root(W/R) = square root( 0.25/(3.3x1000) ) = 0.0087038828 = 8.7 mA 19. A half-watt is equal to how many milliwatts? A. 5,000 mW B. 5 mW C. 500 mW D. 50 mW Answer: Option C 20. Three hundred joules of energy are consumed in 15 s. The power is A. 2,000 W B. 2W C. 20 W D. 200 W Answer: Option C 21. The power rating of a carbon-composition resistor that is to handle up to 1.2 W should be A. 2W B. 1W C. 5W D. 0.5 W Answer: Option A 22. How much continuous current can be drawn from a 60 Ah battery for 14 h? A. 42.8 A @SDM 73 SDM SERVICES https://sites.google.com/site/sdmservice15/ B. 428 A C. 4.28 A D. 4.2 A Answer: Option C 23. A 75 load uses 2 W of power. The output voltage of the power supply is approximately A. 120 V B. 1.2 V C. 12 V D. 6V Answer: Option C 24. When the current through a 12 k A. 7.68 mW B. 768 mW C. 7.68 W D. 76.8 W resistor is 8 mA, the power is Answer: Option B 25. A 68 resistor is connected across the terminals of a 3 V battery. The power dissipation of the resistor is A. 132 mW B. 13.2 mW C. 22.6 mW D. 226 mW Answer: Option A Parallel Circuits A. 55 B. 5.5 C. 50 D. 9 Answer: Option B 2. The total resistance of a parallel circuit is 50 . If the total current is 120 mA, the current through @SDM 74 SDM SERVICES https://sites.google.com/site/sdmservice15/ the 270 resistor that makes up part of the parallel circuit is approximately A. 22 mA B. 120 mA C. 220 mA D. 50 mA Answer: Option A 3. The currents into a junction flow along two paths. One current is 4 A and the other is 3 A. The total current out of the junction is A. 1A B. 7A C. unknown D. the larger of the two Answer: Option B 4. When an additional resistor is connected across an existing parallel circuit, the total resistance A. remains the same B. decreases by the value of the added resistor C. increases by the value of the added resistor D. decreases Answer: Option D 5. When a 1.6 k resistor and a 120 A. greater than 1.6 k B. greater than 120 C. less than 120 D. less than 100 resistor are connected in parallel, the total resistance is but less than 1.6 k but greater than 100 Answer: Option C 6. If there are a total of 120 mA into a parallel circuit consisting of three branches, and two of the branch currents are 40 mA and 10 mA, the third branch current is A. 50 mA B. 70 mA C. 120 mA D. 40 mA Answer: Option B @SDM 75 7. SDM SERVICES https://sites.google.com/site/sdmservice15/ Three lights are connected in parallel across a 120 volt source. If one light burns out, A. the remaining two will glow dimmer B. the remaining two will glow brighter C. the remaining two will not light D. the remaining two will glow with the same brightness as before Answer: Option D 8. Four equal-value resistors are connected in parallel. Ten volts are applied across the parallel circuit and 2 mA are measured from the source. The value of each resistor is A. 12.5 B. 200 C. 20 K D. 50 Answer: Option C Explanation: 10/(R/4) = 2 mA 40/R = 2 mA R = 40/2 mA = 40/0.002 A = 20000 kohm (20 kohm) 9. A set of Christmas tree lights is connected in parallel across a 110 V source. The filament of each light bulb is 1.8 k . The current through each bulb is approximately A. 610 mA B. 18 mA C. 110 mA D. 61 mA Answer: Option D 10. The power dissipation in each of four parallel branches is 1.2 W. The total power dissipation is A. 1.2 W B. 4.8 W C. 0.3 W D. 12 W Answer: Option B @SDM 76 SDM SERVICES https://sites.google.com/site/sdmservice15/ 11. A 470 resistor, a 220 approximately A. 790 B. 470 C. 60 D. 30 resistor, and a 100 resistor are all in parallel. The total resistance is Answer: Option C Explanation: 1/R = (1/470 + 1/220 + 1/100) R = 59.98 ohm 12. Five light bulbs are connected in parallel across 110 V. Each bulb is rated at 200 W. The current through each bulb is approximately A. 2.2 A B. 137 mA C. 1.8 A D. 9.09 A Answer: Option C 13. Four resistors of equal value are connected in parallel. If the total voltage is 15 V and the total resistance is 600 , the current through each parallel resistor is A. 25 mA B. 100 mA C. 6.25 mA D. 200 mA Answer: Option C 14. Five 100 A. 25 B. 500 C. 100 D. 20 resistors are connected in parallel. If one resistor is removed, the total resistance is Answer: Option A Explanation: 1/R = 1/R1 + 1/R2 + 1/R3 + 1/R4 1/R = 1/100 + 1/100 + 100 + 1/100 1/R = 4/100 @SDM 77 SDM SERVICES https://sites.google.com/site/sdmservice15/ 1/R = 1/25 Therefore R = 25 ohm. 15. Four 8 speakers are connected in parallel to the output of an audio amplifier. If the maximum voltage to the speakers is 12 V, the amplifier must be able to deliver to the speakers A. 18 W B. 1.5 W C. 48 W D. 72 W Answer: Option D 16. In a certain three-branch parallel circuit, R1 has 12 mA through it, R2 has 15 mA through it, and R3 has 25 mA through it. After measuring a total of 27 mA, you can say that A. R3 is open B. R1 is open C. R2 is open D. the circuit is operating properly Answer: Option A 17. A sudden increase in the total current into a parallel circuit may indicate A. a drop in source voltage B. an open resistor C. an increase in source voltage D. either a drop in source voltage or an open resistor Answer: Option C 18. The following currents are measured in the same direction in a three-branch parallel circuit: 200 mA, 340 mA, and 700 mA. The value of the current into the junction of these branches is A. 200 mA B. 540 mA C. 1.24 A D. 900 mA Answer: Option C 19. The following resistors are in parallel across a voltage source: 220 with the least current is A. , 470 , and 560 . The resistor 220 @SDM 78 SDM SERVICES https://sites.google.com/site/sdmservice15/ B. 470 C. 560 D. impossible to determine without knowing the voltage Answer: Option C 20. Three 47 resistors are connected in parallel across a 110 volt source. The current drawn from the source is approximately A. 2.3 A B. 780 mA C. 47 mA D. 7.06 A Answer: Option D 21. There is a total of 800 mA of current into four parallel resistors. The currents through three of the resistors are 40 mA, 70 mA, and 200 mA. The current through the fourth resistor is A. 490 mA B. 800 mA C. 310 mA D. 0A Answer: Option A 22. Four resistors are connected in parallel. Fifteen mA flows through resistor R. If the second resistor is 2R, the third resistor 3R, and the fourth resistor 4R, the total current in the circuit is A. 60 mA B. 15 mA C. 135 mA D. 31.25 mA Answer: Option D 23. If one of the resistors in a parallel circuit is removed, the total resistance A. decreases B. increases C. remains the same D. doubles Answer: Option B 24. Six resistors are in parallel. The two lowest-value resistors are both 1.2 k . The total resistance @SDM 79 SDM SERVICES https://sites.google.com/site/sdmservice15/ A. is less than 6 k B. is greater than 1.2 k C. is less than 1.2 k D. is less than 600 Answer: Option D 25. In a five-branch parallel circuit, there are 12 mA of current in each branch. If one of the branches opens, the current in each of the other four branches is A. 48 mA B. 12 mA C. 0A D. 3 mA Answer: Option B Circuit Theorems and Conversions 1. Find the Thevenin equivalent (VTH and RTH) between terminals A and B of the circuit given below. A. 4.16 V, 120 B. 41.6 V, 120 C. 4.16 V, 70 D. 41.67 V, 70 Answer: Option D 2. A certain current source has the values IS = 4 µA and RS = 1.2 M source are A. 4.8 . The values for an equivalent voltage V, 1.2 M @SDM 80 SDM SERVICES https://sites.google.com/site/sdmservice15/ B. 1 V, 1.2 M C. 4.8 V, 4.8 M D. 4.8 V, 1.2 M Answer: Option D 3. Find the total current through R3 in the given circuit. A. 7.3 mA B. 5.5 mA C. 12.8 mA D. 1.8 mA Answer: Option D @SDM 81 SDM SERVICES https://sites.google.com/site/sdmservice15/ 4. A 680 load resistor, RL, is connected across a constant current source of 1.2 A. The internal source resistance, RS, is 12 k . The load current, RL, is A. 0A B. 1.2 A C. 114 mA D. 1.14 A Answer: Option D 5. Find the current through R2 of the given circuit. A. 30.7 mA B. 104 mA C. 74 mA D. 134 mA Answer: Option D 6. Determine IN for the circuit consisting of VS, R1, R2, and R3 shown in the given circuit. @SDM 82 SDM SERVICES https://sites.google.com/site/sdmservice15/ A. 676 mA B. 245 mA C. 431 mA D. 75 mA Answer: Option B 7. A 120 V voltage source has a source resistance, RS, of 60 A. 2A B. 4A C. 200 mA D. 400 mA . The equivalent current source is Answer: Option A 8. A 12 V source has an internal resistance of 90 source, the load power, PL, is A. 2.38 mW B. 2.38 W C. 238 mW D. 23.8 W . If a load resistance of 20 is connected to the voltage Answer: Option C 9. In a two-source circuit, one source acting alone produces 12 mA through a given branch. The other source acting alone produces 10 mA in the opposite direction through the same branch. The actual current through the branch is A. 22 mA B. 12 mA C. 10 mA D. 2 mA Answer: Option D @SDM 83 SDM SERVICES https://sites.google.com/site/sdmservice15/ 10. Find the current through R1 in the given circuit. A. 0.16 A B. 0.24 A C. 0.2 A D. 0.04 A Answer: Option A 11. What is the Thevenin equivalent (VTH and RTH) for the circuit given? A. 6.4 V, 422 B. 6.4 V, 560 C. 6.4 V, 680 D. 30 V, 422 Answer: Option A 12. Referring to the given circuit, the voltage and current for the load resistor, RL, is A. 450 mV, 4.5 mA B. 4.50 V, 45 mA C. 4.50 V, 4.5 mA D. 450 mV, 45 mA Answer: Option C @SDM 84 SDM SERVICES https://sites.google.com/site/sdmservice15/ 13. Find the current in R2 of the given circuit, using the superposition theorem. A. 16.7 mA B. 33.3 mA C. 50 mA D. 16.6 mA Answer: Option C 14. A 470 RL is connected across a voltage source, VS, of 120 V. The source's internal resistance, RS, is 12 . What is the output voltage across the load? A. 120 V B. 0V C. 117 V D. 12 V Answer: Option C 15. A 2 RL is connected across a voltage source, VS, of 110 V. The source's internal resistance is 24 What is the output voltage across the load? . @SDM 85 SDM SERVICES https://sites.google.com/site/sdmservice15/ A. 8.5 V B. 85 V C. 0V D. 110 V Answer: Option A 16. An 18 V source has an internal resistance of 70 voltage source, the load power, PL, is A. 0W B. 1W C. 175 mW D. 18 mW . If a load resistance of 33 is connected to the Answer: Option B 17. A certain voltage source has the values VS = 30 V and RS = 6 source are A. 5 A, 6 B. 30 A, 6 C. 5 A, 30 D. 30 A, 5 . The values for an equivalent current Answer: Option A 18. A 120 load is connected across an ideal voltage source with VS = 12 V. The voltage across the load A. is 0 V B. is 12 V C. is 120 V D. cannot be determined Answer: Option B 19. Find the Norton circuit, that is, IIN and RN, for the circuit given below. A. 478 mA, 12.8 B. 750 mA, 12.8 C. 478 mA, 6.8 @SDM 86 SDM SERVICES https://sites.google.com/site/sdmservice15/ D. 750 mA, 6.8 Answer: Option A 20. A 120 load is load is connected across a voltage source with VS = 12 V and RS = 8 A. 11.25 V B. 0V C. 12 V D. 1.13 V . The voltage across the Answer: Option A 21. Find RN for the circuit given. A. 34 B. 68 C. 120 D. 154 Answer: Option D 22. Referring to circuit given, if R1 is changed to a 68 A. resistor, what will be the current through it? 0.16 A @SDM 87 SDM SERVICES https://sites.google.com/site/sdmservice15/ B. 0.24 A C. 0.2 A D. 0.04 A Answer: Option A 23. Find the Thevenin equivalent (VTH and RTH) between terminals A and B of the circuit given. A. 562 mV, 167 B. 5.62 V, 167 C. 5.62 V, 188 D. 562 mV, 188 Answer: Option B 24. Referring to the given circuit, determine V and R if a 68 TH TH across R2 and R3. A. 3.3 V, 148 B. 330 mV, 148 C. 3.3 V, 68 D. 330 mV, 68 resistor is connected in parallel Answer: Option A @SDM 88 SDM SERVICES https://sites.google.com/site/sdmservice15/ 25. A 12 mA current source has an internal resistance, R , of 1.2 k S A. 144 V B. 14.4 V C. 7.2 V D. 72 mV . The equivalent voltage source is Answer: Option B Magnetism and Electromagnetism 1. When the speed at which a conductor is moved through a magnetic field is increased, the induced voltage A. increases B. decreases C. remains constant D. reaches zero Answer: Option A 2. The induced voltage across a coil with 250 turns that is located in a magnetic field that is changing at a rate of 8 Wb/s is A. 1,000 V B. 2,000 V C. 31.25 V D. 3,125 V Answer: Option B 3. For a given wirewound core, an increase in current through the coil A. reverses the flux lines @SDM 89 SDM SERVICES https://sites.google.com/site/sdmservice15/ C. increases the flux density D. causes no change in flux density Answer: Option C 4. If the cross-sectional area of a magnetic field increases, but the flux remains the same, the flux density A. increases B. decreases C. remains the same D. doubles Answer: Option B 5. When the current through the coil of an electromagnet reverses, the A. direction of the magnetic field reverses B. direction of the magnetic field remains unchanged C. magnetic field expands D. magnetic field collapses Answer: Option A 6. What is the reluctance of a material that has a length of 0.07 m, a cross-sectional area of 0.014 m2, and a permeability of 4,500 A. 1111 At/Wb B. 111 At/Wb C. 11 At/Wb D. 1 At/Wb Wb/At × m? Answer: Option A 7. A coil of wire is placed in a changing magnetic field. If the number of turns in the coil is decreased, the voltage induced across the coil will A. increase B. decrease C. remain constant D. be excessive Answer: Option B 8. What is the flux density when the flux is 5.5 Wb and the cross-sectional area is 6 × 10–3 m2? @SDM 90 SDM SERVICES https://sites.google.com/site/sdmservice15/ A. 91.7 T B. 917 T C. 91 T D. 9.7 T Answer: Option B 9. The unit for reluctance is A. tesla B. At/Wb C. At/m D. Wb Answer: Option B 10. If the steel disk in a crankshaft position sensor has stopped with the tab in the magnet's air gap, the induced voltage A. increases B. decreases C. is zero D. will remain constant Answer: Option C 11. There is 900 mA of current through a wire with 40 turns. What is the reluctance of the circuit if the flux is 400 Wb? A. 14,400 At/Wb B. 1,440 At/Wb C. 9,000 At/Wb D. 90,000 At/Wb Answer: Option D 12. A basic one-loop dc generator is rotated at 90 rev/s. How many times each second does the dc output voltage peak (reach maximum)? A. 90 B. 180 C. 270 D. 360 Answer: Option B @SDM 91 13. SDM SERVICES https://sites.google.com/site/sdmservice15/ What is the flux density in a magnetic field in which the flux in 0.1 m2 is 600 A. 6,000 B. 600 C. 600 T D. 6T Wb? T T Answer: Option A 14. The unit for permeability is A. Wb/At × m B. At/m C. At/Wb D. Wb Answer: Option A 15. What is the magnetomotive force in a 75-turn coil of wire when there are 4 A of current through it? A. 18.75 At B. 30 At C. 300 At D. 187 At Answer: Option C 16. The direction of a magnetic field within a magnet is A. from south to north B. from north to south C. back to front D. front to back Answer: Option A 17. When the north poles of two bar magnets are brought close together, there will be A. no force B. a downward force C. a force of attraction D. a force of repulsion Answer: Option D @SDM 92 SDM SERVICES https://sites.google.com/site/sdmservice15/ 18. The ability of a material to remain magnetized after removal of the magnetizing force is known as A. permeability B. reluctance C. hysteresis D. retentivity Answer: Option D 19. The voltage induced across a certain coil is 200 mV. A 120 The induced current is A. 1.7 mA B. 16 mA C. 12 mA D. 120 mA resistor is connected to the coil terminals. Answer: Option A 20. The induced voltage across a stationary conductor in a stationary magnetic field is A. zero B. reversed in polarity C. increased D. decreased Answer: Option A 21. An electromagnetic field exists only when there is A. an increasing current B. decreasing current C. voltage D. current Answer: Option D 22. When a solenoid is activated, the force that moves the plunger is A. an electromagnetic field B. a permanent magnetic field C. varying voltage D. a steady current Answer: Option A @SDM 93 SDM SERVICES https://sites.google.com/site/sdmservice15/ 23. What is the magnetomotive force (mmf) of a wire with 8 turns carrying three amperes of current? A. 2,400 At B. 240 At C. 24 At D. 2.4 At Answer: Option C 24. If a loop in a basic dc generator suddenly begins rotating at a faster speed, the induced voltage A. remains unchanged B. reverses polarity C. increases D. decreases Answer: Option C Capacitors 1. A 10 F, 20 F, 22 A. 2.43 F B. 4.86 F C. 100 F D. 152 F F, and 100 F capacitor are in parallel. The total capacitance is Answer: Option D 2. A capacitor and a resistor are connected in series to a sine wave generator. The frequency is set so that the capacitive reactance is equal to the resistance and, thus, an equal amount of voltage appears across each component. If the frequency is increased A. VR > VC B. VC > VR C. VR = VC D. VR and VC = 0 Answer: Option A 3. A capacitor of 0.02 A. F is larger than 0.000020 F @SDM 94 SDM SERVICES https://sites.google.com/site/sdmservice15/ B. 200,000 pF C. 2,000 pF D. all of the above Answer: Option C 4. In Question 6, the capacitor will reach full charge in a time equal to approximately A. 6 RC B. 5 RC C. RC D. none of the above Answer: Option B 5. What is the capacitance when Q = 60 A. 720 B. 5 C. 50 F D. 12 F C and V = 12 V? F F Answer: Option B 6. A 0.47 F capacitor is across a 2 kHz sine wave signal source. The capacitive reactance is A. 170 B. 17 C. 0.000169 D. 1.7 Answer: Option A 7. Four 0.15 F capacitors are in parallel. The total capacitance is A. 0.15 F B. 0.30 F C. 0.6 F D. 0.8 F Answer: Option C @SDM 95 8. SDM SERVICES https://sites.google.com/site/sdmservice15/ Which of the following capacitors is polarized? A. mica B. ceramic C. plastic-film D. electrolytic Answer: Option D 9. A capacitor of 2,000 pF is greater than A. 0.02 B. 0.002 C. 0.0002 D. 0.0000002 F F F F Answer: Option C 10. A 220 resistor is in series with a 2.2 A. 48 B. 480 s C. 2.42 s D. 24 F capacitor. The time constant is s s Answer: Option B 11. A 4.7 M resistor is in series with a 0.015 F capacitor. The combination is across a 12 V source. How long does it take the capacitor to fully charge? A. 35 ms B. 352 ms C. 3.5 s D. 70.5 ms Answer: Option B 12. A sine wave voltage is applied across a capacitor. When the frequency of the voltage is decreased, the current A. increases @SDM 96 SDM SERVICES https://sites.google.com/site/sdmservice15/ B. remains constant C. decreases D. ceases Answer: Option C 13. Of the following capacitors, which one has the highest dielectric constant? A. air B. mica C. glass D. paper Answer: Option C 14. A 0.01 F capacitor equals how many picofarads? A. 100 pF B. 1,000 pF C. 10,000 pF D. 100,000 pF Answer: Option C 15. A 12 kHz voltage is applied to a 0.33 value of the voltage? A. 8V B. 80 V C. 80 mV D. 800 mV F capacitor, and 200 mA of rms current is measured. What is the Answer: Option A 16. A 0.00022 F capacitor equals how many microfarads? A. 22 B. 220 C. 2,200 D. 22,200 F F F F Answer: Option B 17. Two series capacitors (one 2 F, the other of unknown value) are charged from a 24 V source. The 2 F capacitor is charged to 16 V and the other to 8 V. The value of the unknown capacitor is @SDM 97 SDM SERVICES https://sites.google.com/site/sdmservice15/ A. 1 F B. 2 F C. 4 F D. 8 F Answer: Option C 18. A 330 pF capacitor and a 220 pF capacitor are each connected across a 6 V dc source. The voltage across the 330 pF capacitor is A. 3V B. 6V C. 4V D. 0V Answer: Option B 19. A 2 F, a 4 F, and a 10 A. 2 F B. 4 F C. 10 F D. 1.5 F F capacitor are connected in series. The total capacitance is less than Answer: Option D 20. When the plate area of a capacitor increases, A. the capacitance increases B. the capacitance decreases C. the capacitance is unaffected D. the voltage it can withstand increases. Answer: Option A 21. Two 0.68 F capacitors are connected in series across a 10 kHz sine wave signal source. The total capacitive reactance is @SDM 98 SDM SERVICES https://sites.google.com/site/sdmservice15/ A. 46.8 B. 4.68 C. 23.41 D. 11.70 Answer: Option A 22. An uncharged capacitor and a 1 k resistor are connected in series with a switch and a 6 V battery. At the instant the switch is closed, the voltage across the capacitor is A. 6V B. 3V C. 2V D. 0V Answer: Option D 23. When the voltage across a capacitor is tripled, the stored charge A. triples B. is cut to one-third C. stays the same D. doubles Answer: Option A Transformers 1. What kVA rating is required for a transformer that must handle a maximum load current of 8 A with a secondary voltage of 2 kV? A. 4 kVA B. 0.25 kVA C. 16 kVA D. 8 kVA Answer: Option C 2. The turns ratio required to match an 80 A. 80 B. 20 C. 4 D. 2 source to a 320 load is @SDM 99 SDM SERVICES https://sites.google.com/site/sdmservice15/ Answer: Option D 3. When the turns ratio of a transformer is 20 and the primary ac voltage is 12 V, the secondary voltage is A. 12 V B. 120 V C. 240 V D. 2,400 V Answer: Option C 4. If a transformer has 50 turns in the primary winding and 10 turns in the secondary winding, what is the reflective resistance if the secondary load resistance is 250 ? A. 250 B. 25 C. 6,250 D. 62,500 Answer: Option C 5. A certain transformer has 400 turns in the primary winding and 2,000 turns in the secondary winding. The turns ratio is A. 0.2 B. 0.4 C. 5 D. 25 Answer: Option C 6. The primary winding of a transformer has 110 V ac across it. What is the secondary voltage if the turns ratio is 8? A. 8.8 V B. 88 V C. 880 V D. 8,800 V Answer: Option C Explanation: V2/V1 = N2/N1 Turns ratio = N2/N1 = 8. V2/110 = 8 V2 = 8 x 110 @SDM 100 SDM SERVICES https://sites.google.com/site/sdmservice15/ V2 = 880v. 7. To step 110 V ac down to 20 V ac, the turns ratio must be A. 5.5 B. 18 C. 0.18 D. 0.018 Answer: Option C Explanation: Vp/Vs = Np/Ns Vs = (Ns/Np)Vp We required turns ratio i.e., (Ns/Np) = Vs/Vp = 20/110 = 0.181818182 [Note: p - primary; s - secondary] For step down transfer, the turns ratio will be less than 1. 8. The mutual inductance when k = 0.65, L1 = 2 A. 2 mH B. 2 H C. 4 H D. 8 H H, and L2 = 5 H is Answer: Option B 9. If 25 W of power are applied to the primary of an ideal transformer with a turns ratio of 10, the power delivered to the secondary load is A. 25 W B. 0W C. 250 W D. 2.5 W Answer: Option A @SDM 101 SDM SERVICES https://sites.google.com/site/sdmservice15/ 10. A transformer with a 110 V primary has a 15:1 turns ratio. The load resistance, RL, is 120 approximate voltage across the load? A. 7.3 V B. 73 V C. 88 V D. 880 V . What is the Answer: Option A 11. How many primary volts must be applied to a transformer with a turns ratio of 0.1 to obtain a secondary voltage of 9 V? A. 9V B. 90 V C. 900 V D. 0.9 V Answer: Option B Explanation: We know that, V2/V1 = N2/N1. Given V2 = 9v, N2/N1 = 0.1 Therefore, 9v/V1 = 0.1 V1 = 9v/0.1 = 90v. 12. In a certain loaded transformer, the secondary voltage is one-fourth the primary voltage. The secondary current is A. one-fourth the primary current B. four times the primary current C. equal to the primary current D. one-fourth the primary current and equal to the primary current Answer: Option B 13. A certain transformer has a turns ratio of 1 and a 0.85 coefficient of coupling. When 2 V ac is applied to the primary, the secondary voltage is A. 1.7 V B. 0.85 V C. 1V D. 0V Answer: Option A 14. The primary coil of a transformer is connected to a 60 V ac source. The secondary coil is connected to a 330 load. The turns ratio is 3:1. What is the secondary voltage? @SDM 102 SDM SERVICES https://sites.google.com/site/sdmservice15/ A. 2V B. 20 V C. 180 V D. 18 V Answer: Option B 15. The primary winding of a power transformer should always be A. open B. shorted C. switched D. fused Answer: Option D 16. A certain amplifier has 600 internal resistance looking from its output. In order to provide maximum power to a 4 speaker, what turns ratio must be used in the coupling transformer? A. 8 B. 0.8 C. 0.08 D. 80 Answer: Option C 17. A transformer A. changes ac to dc B. changes dc to ac C. steps up or down dc voltages D. steps up or down ac voltages Answer: Option D 18. The primary of a transformer is connected to a 6 V battery. The turns ratio is 1:3 and the secondary load, RL, is 100 . The voltage across the load is A. 0V B. 6V C. 18 V D. 2V Answer: Option A @SDM 103 SDM SERVICES https://sites.google.com/site/sdmservice15/ 19. To step 120 V ac up to 900 V ac, the turns ratio must be A. 75 B. 750 C. 7.5 D. 0.13 Answer: Option C 20. When a 200 load resistor is connected across the secondary winding of a transformer with a turns ratio of 4, the source "sees" a reflective load of A. 50 B. 12.5 C. 800 D. 0 Answer: Option B 21. In a certain transformer, the input power to the primary is 120 W. If 8.5 W are lost to the winding resistance, what is the output power to the load, neglecting any other issues? A. 0W B. 14.1 W C. 111.5 W D. 1,020 W Answer: Option C 22. When a 6 V battery is connected across the primary of a transformer with a turns ratio of 8, the secondary voltage is A. 0V B. 6V C. 48 V D. 0.75 V Answer: Option A 23. What is the coefficient of coupling for a transformer in which 4% of the total flux generated in the primary does not pass through the secondary? A. 0.4 B. 4 @SDM 104 SDM SERVICES https://sites.google.com/site/sdmservice15/ C. 9.6 D. 0.96 Answer: Option D 24. A transformer has a 1:6 turns ratio and a secondary coil load resistance of 470 seen by the source is A. 1.3 B. 7.8 C. 78 D. 13 . The load resistance as Answer: Option D RL Circuits 1. A 1.5 k resistor and a coil with a 2.2 k power factor is A. 564 B. 0.564 C. 6.76 D. 55.7 inductive reactance are in series across an 18 V ac source. The Answer: Option B 2. The voltages in Problem 5 are measured at a certain frequency. To make the resistor voltage less than the inductor voltage, the frequency is A. increased B. decreased C. doubled D. not a factor Answer: Option A 3. In a series RL circuit, 12 V rms is measured across the resistor, and 14 V rms is measured across the inductor. The peak value of the source voltage is A. 18.4 V B. 26.0 V C. 2V D. 20 V Answer: Option B @SDM 105 4. SDM SERVICES https://sites.google.com/site/sdmservice15/ Referring to Problem 18, the circuit impedance is A. 458 –76° B. 4.58 –76° C. 458 76° D. 4.58 76° Answer: Option C 5. To increase the current in a series RL circuit, the frequency A. should be increased B. should be decreased C. should be constant D. cannot be determined without values Answer: Option B 6. A 470 resistor and a coil with 125 inductive reactance are in parallel. Both components are across a 15 V ac voltage source. Current through the inductor is A. 152 mA B. 32 mA C. 12 mA D. 120 mA Answer: Option D 7. A 1.2 k resistor is in series with a 15 mH coil across a 10 kHz ac source. The magnitude of the total impedance is A. 152.6 B. 1,526 C. 1,200 D. 942 Answer: Option B 8. When the frequency is decreased, the impedance of a parallel RL circuit A. increases B. decreases C. remains constant D. is not a factor @SDM 106 SDM SERVICES https://sites.google.com/site/sdmservice15/ Answer: Option B 9. A 470 resistor and a 200 mH coil are in parallel. Both components are across a 1.5 kHz ac source. The total admittance of the circuit, in polar form, is A. 12.60 –76° mS B. 12.18 76° mS C. 218 D. 12.18 –76° mS –76° mS Answer: Option D 10. Referring to Problem 23, the reactive power is A. 10 mVAR B. 100 mVAR C. 6.76 mVAR D. 148 mVAR Answer: Option B 11. A 12 k resistor is in series with a 90 mH coil across an 8 kHz ac source. Current flow in the circuit, expressed in polar form, is I = 0.3 0° mA. The source voltage, expressed in polar form, is A. 3.84 20.6° V B. 12.8 20.6° V C. 0.3 D. 13.84 20.6° V 69.4° V Answer: Option A 12. A 140 resistor is in parallel with an inductor having 60 inductive reactance. Both components are across a 12 V ac source. The magnitude of the total impedance is A. 5.51 B. 55.15 C. 90 D. 200 Answer: Option B 13. When the frequency of the voltage applied to a series RL circuit is decreased, the impedance @SDM 107 SDM SERVICES https://sites.google.com/site/sdmservice15/ A. decreases B. increases C. does not change D. cannot be determined without values Answer: Option A 14. In a parallel RL circuit, there are 3 A rms in the resistive branch and 3 A rms in the inductive branch. The total rms current is A. 6A B. 424 mA C. 4.24 A D. 42.4 A Answer: Option C 15. A 47 resistor is in series with an inductive reactance of 120 expressed in polar form, is A. 47 B. 120 68.6° C. 129 31.4° D. 129 68.6° across an ac source. The impedance, 68.6° Answer: Option D 16. When the resistor voltage in a series RL circuit becomes less than the inductor voltage, the phase angle A. increases B. decreases C. is not affected D. cannot be determined Answer: Option A 17. Which of the following power factors results in less energy loss in an RL circuit? A. 1 B. 0.8 C. 0.4 D. 0.2 Answer: Option D 18. Referring to Problem 20, @SDM 108 SDM SERVICES https://sites.google.com/site/sdmservice15/ A. the applied voltage lags the current B. the current lags the applied voltage C. the applied voltage and the current are in phase D. the current lags the applied voltage by 90° Answer: Option B 19. A 3.3 k resistor and a 120 mH coil are in parallel. Both components are across a 2 kHz, 12 V ac source. The total current in the circuit is A. 8.74 mA B. 874 mA C. 874 A D. 8.74 A Answer: Option A 20. When the frequency of the voltage applied to a series RL circuit is increased, the phase angle A. decreases B. increases C. does not change D. cannot be determined without values Answer: Option B 21. If a load is purely inductive and the reactive power is 12 VAR, the apparent power is A. 0 VA B. 12 VA C. 6 VA D. 24 VA Answer: Option B 22. If the frequency is halved and the resistance is doubled, the impedance of a series RL circuit A. doubles B. halves C. remains constant D. cannot be determined without values Answer: Option D @SDM 109 SDM SERVICES https://sites.google.com/site/sdmservice15/ Passive Filters 1. In a certain parallel resonant band-pass filter, the resonant frequency is 14 kHz. If the bandwidth is 4 kHz, the lower frequency A. is 7 kHz B. is 10 kHz C. is 12 kHz D. cannot be determined Answer: Option C 2. An RL low-pass filter consists of a 5.6 mH coil and a 3.3 k resistor. The circuit's critical frequency is A. 93.8 kHz B. 93.8 Hz C. 861 Hz D. 86.12 kHz resistor. The output voltage is taken across the Answer: Option A 3. In a series resonant band-pass filter, a lower value of Q results in A. a higher resonant frequency B. a smaller bandwidth C. a higher impedance D. a larger bandwidth Answer: Option D 4. The maximum output voltage of a certain low-pass filter is 15 V. The output voltage at the critical frequency is A. 0V B. 15 V C. 10.60 V D. 21.21 V Answer: Option C 5. A parallel resonant band-pass filter consists of a 90 resistor in series with a parallel network made up of a 60 mH coil and a 0.02 F capacitor. The output is taken across the capacitor/coil. The coil winding has a resistance of 20 . What is the center frequency of the filter? A. 459 Hz @SDM 110 SDM SERVICES https://sites.google.com/site/sdmservice15/ B. 4,591 Hz C. 999 Hz D. 2,176 Hz Answer: Option B 6. An RL high-pass filter consists of a 470 The circuit's critical frequency is A. 125 Hz B. 1,250 Hz C. 564 Hz D. 5,644 Hz resistor and a 600 mH coil. The output is taken across the coil. Answer: Option A 7. Referring to Problem 23, what will the output voltage be if the coil's internal resistance is neglected? A. 0V B. 200 mV C. 11.1 mV D. 111 mV Answer: Option A 8. A parallel resonant band-pass filter consists of a 6.8 resistor in series with a parallel network made up of an 8 H coil and a 120 pF capacitor. The output is taken across the capacitor/coil. Assume RW = 0 What is the center frequency of the filter? A. 5.14 MHz B. 514 kHz C. 5.03 MHz D. 503 kHz . Answer: Option A 9. A series resonant band-pass filter consists of a 2 mH coil, a 0.005 F capacitor, and a 120 resistor. The winding resistance of the coil is 12 . The output voltage is taken off the resistor. Input voltage is 12 Vrms. What is the output voltage magnitude at the center frequency (f0 )? A. 10.9 V B. 1.09 V C. 1.1 V D. 12 V Answer: Option A @SDM 111 SDM SERVICES https://sites.google.com/site/sdmservice15/ 10. The same signal in Problem 2 is applied to an RC high-pass filter. If the reactance is zero at the input frequency, the output voltage is A. 18 V peak-to-peak B. zero C. 9 V peak-to-peak D. 12.73 V peak-to-peak Answer: Option A 11. An RC low-pass filter consists of a 120 resistor and a 0.002 the capacitor. The circuit's critical frequency is A. 333 kHz B. 633 kHz C. 331 kHz D. 60 kHz F capacitor. The output is taken across Answer: Option B 12. Referring to Problem 8, assume the input voltage is 15 V ac. What is the output voltage at the critical frequency,fc? A. 0V B. 7.07 V C. 15 V D. 10.6 V Answer: Option D 13. Referring to Problem 21, the filter's bandwidth is A. 11.5 Hz B. 530 Hz C. 53 Hz D. 106 Hz Answer: Option C 14. Referring to Problem 15, if the input voltage is a 6 V sine wave with a dc level of 10 V, what is the output voltage magnitude? A. 6V B. 597 mV @SDM 112 SDM SERVICES https://sites.google.com/site/sdmservice15/ C. 5.97 V D. 0V Answer: Option C 15. In a certain low-pass filter, fc = 3.5 kHz. Its passband is A. 0 Hz to 3.5 kHz B. 0 Hz C. 3.5 kHz D. 7 kHz Answer: Option A 16. An RC high-pass filter consists of an 820 than R at an input frequency of 12 kHz? A. 81 B. 161 C. 0.161 D. 220 resistor. What is the value of C so that Xc is ten times less F F F F Answer: Option C 17. A series resonant band-stop filter consists of a 68 resistor, a 110 mH coil, and a 0.02 F capacitor. The internal resistance, RW, of the coil is 4 . Input voltage is 200 mV. Output voltage is taken across the coil and capacitor in series. What is the output voltage magnitude at f0 ? A. 1.1 mV B. 11.1 mV C. 111 mV D. 200 mV Answer: Option B 18. A sinusoidal voltage with a peak-to-peak value of 18 V is applied to an RC low-pass filter. If the reactance at the input frequency is zero, the output voltage is A. 18 V peak-to-peak B. zero C. 9 V peak-to-peak D. 12.74 V peak-to-peak Answer: Option B 19. Vout = 500 mV, and Vin = 1.3 V. The ratio Vout/ Vin expressed in dB is @SDM 113 SDM SERVICES https://sites.google.com/site/sdmservice15/ A. 0 dB B. 8.30 dB C. –8.30 dB D. 0.8 dB Answer: Option C 20. Referring to Problem 8, assume the input voltage is 15 V dc. What is the output voltage? A. 0V B. 15 V C. 7.07 V D. 10.6 V Answer: Option B 21. At a certain frequency, the output voltage of a filter is 6 V and the input is 12 V. The voltage ratio in decibels is A. 6.02 dB B. –6.02 dB C. 12.04 dB D. –12.04 dB Answer: Option B 22. An RC high-pass filter consists of a 0.2 F capacitor and a 220 the resistor. The circuit's critical frequency is A. 723 Hz B. 7,234 Hz C. 362 Hz D. 3,617 Hz resistor. The output is taken across Answer: Option D Time Response of Reactive Circuits 1. When a 15 V input pulse with a width equal to two time constants is applied to an RC integrator, the capacitor charges to A. 15 V B. 12.9 V @SDM 114 SDM SERVICES https://sites.google.com/site/sdmservice15/ C. 8.6 V D. 19.45 V Answer: Option B 2. An integrator consists of a 3.3 k resistor and a 2 the input. How much will the capacitor charge? A. 10.3 V B. 30 V C. 12.09 V D. 17.91 V F capacitor. A single 30 V, 6 ms pulse is applied to Answer: Option D 3. Referring to Problem 5, how long will it take the capacitor to discharge if the internal resistance of the pulse source is 100 ? A. 300 s B. 600 s C. 900 s D. 1.5 ms Answer: Option D 4. With an RL integrator, at the instant of the rising pulse edge, A. all the input voltage is across the resistor B. all the input voltage is across the inductor C. 63 percent of the input voltage is across the resistor D. 63 percent of the input voltage is across the inductor Answer: Option B 5. When a 12 V input pulse with a width equal to one time constant is applied to an RC integrator, the capacitor charges to A. 0V B. 12 V C. 6.3 V D. 7.56 V Answer: Option D 6. Referring this circuit, determine the maximum output voltage when a single pulse is applied as shown. The total resistance is 60 . @SDM 115 SDM SERVICES https://sites.google.com/site/sdmservice15/ A. 2.73 V B. 27.33 V C. 30 V D. 2.67 V Answer: Option B 7. A steady-state condition is reached when A. the output voltage reaches the average value of the input voltage B. the output voltage reaches the input voltage C. the output voltage reaches approximately 63% of the input voltage D. the output voltage reaches the effective value of the input voltage Answer: Option A 8. Referring to the give circuit, the output will A. decay to zero at the end of the pulse B. reach 6 V at the end of the pulse C. reach 3.78 V at the end of the pulse D. reach 5.16 V at the end of the pulse Answer: Option A 9. A single 6 V pulse with a width of 600 0.002 s is applied to an integrator consisting of a 150 k resistor and a F capacitor. To what voltage will the capacitor charge? @SDM 116 SDM SERVICES https://sites.google.com/site/sdmservice15/ A. 0V B. 3.78 V C. 5.16 V D. 6V Answer: Option C 10. To understand how the output voltage is shaped by a differentiator, you must consider A. the response to the rising pulse edge B. the response between the rising and falling edges C. the response to the falling pulse edge D. all of the above Answer: Option D 11. If the capacitor in an integrator becomes leaky, A. the time constant will be effectively reduced B. the waveshape of the output voltage across C is altered C. the amplitude of the output is reduced D. all of the above Answer: Option D 12. Referring to the above figure, determine the voltage level that the output will reach during the pulse. A. 0V B. 15 V C. 6.3 V D. 9.45 V Answer: Option D @SDM 117 SDM SERVICES https://sites.google.com/site/sdmservice15/ 13. An RC differentiator acts as a A. low-pass filter B. high-pass filter C. band-pass filter D. band-stop filter Answer: Option B 14. In an RL differentiator, when the input pulse goes from its low level to its high level, A. the inductor prevents a sudden change in voltage B. the inductor prevents a sudden change in current C. voltage across the inductor instantly reaches 63% of input voltage D. voltage across the inductor is zero Answer: Option B 15. Referring this figure, on the falling edge, A. the resistor voltage drops to –5 V and then goes back to zero exponentially B. the resistor voltage jumps to –5 V and then goes back to zero exponentially C. the capacitor voltage remains constant D. the resistor voltage jumps to +5 V and then decreases exponentially to zero Answer: Option B 16. In an RC differentiator, responding to repetitive pulses, the average value of the output A. is zero B. is equal to the input voltage C. is 63 percent of the input voltage D. cannot be determined Answer: Option A @SDM 118 SDM SERVICES https://sites.google.com/site/sdmservice15/ 17. The output of an RC integrator is taken across the A. diode B. capacitor C. resistor D. source Answer: Option B 18. In an RC differentiator, the sum of the capacitor voltage and the resistor voltage at any instant A. must be zero B. must be equal to the applied voltage C. is less than the applied voltage but greater than zero D. cannot be determined Answer: Option B 19. When a 24 V input pulse with a width equal to five time constants is applied to an RC integrator, the capacitor charges to A. 24 V B. 15.12 V C. 20.64 V D. 12 V Answer: Option A 20. If the RC time constant of an integrator is increased, as the time constant is increased A. the capacitor charges more during a pulse and discharges less between pulses B. the capacitor charges less during a pulse and discharges more between pulses C. the capacitor charges more during a pulse and discharges more between pulses D. the capacitor charges less during a pulse and discharges less between pulses Answer: Option D 21. If a periodic pulse waveform has a pulse width and the time between pulses each equal to or greater than five time constants, the capacitor will A. partially charge and fully discharge during each period of the input waveform B. fully charge and partially discharge during each period of the input waveform C. fully charge and fully discharge during each period of the input waveform D. partially charge and partially discharge during each period of the input waveform Answer: Option C @SDM 119 SDM SERVICES https://sites.google.com/site/sdmservice15/ 22. What is the highest frequency contained in a pulse that has a rise and fall time equal to 10 microseconds (10 s)? A. 35 kHz B. 3.5 kHz C. 10 kHz D. 100 kHz Answer: Option A 23. Referring to Problem 7, how much will the capacitor charge if the pulse width is increased to 12 ms? A. 2.51 V B. 25.14 V C. 4.86 V D. 12.76 V Answer: Option B 24. In electronic systems, repetitive-pulse waveforms are encountered A. more often than single pulses B. less often than single pulses C. about as often as single pulses D. twice as often as single pulses Answer: Option A 25. In an RC differentiator, the capacitor A. charges exponentially at a rate depending on the RC time constant B. charges exponentially at a rate depending on the input voltage C. charges when the input voltage is decreasing D. charges to approximately one time constant Answer: Option A @SDM