1. Resistivity of a wire depends on
(A) length
(B) material
(C) cross section area
(D) none of the above.
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B
2. When n resistances each of value r are connected in parallel, then resultant resistance is x. When these n
resistances are connected in series, total resistance is
(A) nx
(B) rnx
(C) x / n
(D) n2 x.
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D
3. Resistance of a wire is r ohms. The wire is stretched to double its length, then its resistance in ohms is
(A) r / 2
(B) 4 r
(C) 2 r
(D) r / 4.
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B
4. Kirchhoff's second law is based on law of conservation of
(A) charge
(B) energy
(C) momentum
(D) mass.
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B
5. The diameter of the nucleus of an atom is of the order of
(A) 10 -31 m
(B) 10 -25 m
(C) 10 -21 m
(D) 10 -14m.
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D
6. The mass of proton is roughly how many times the mass of an electron?
(A) 184,000
(B) 184,00
(C) 1840
(D)184.
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C
7. The charge on an electron is known to be 1.6 x 10 -19 coulomb. In a circuit the current flowing is 1 A. How many
electrons will be flowing through the circuit in a second?
(A) 1.6 x 1019
(B) 1.6 x 10-19
(C) 0.625 x 1019
(D) 0.625 x 1012.
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C
8. Two bulbs marked 200 watt-250 volts and 100 watt-250 volts are joined in series to 250 volts supply. Power
consumed in circuit is
(A) 33 watt
(B) 67 watt
(C) 100 watt
(D) 300 watt.
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B
9. Ampere second could be the unit of
(A) power
(B) conductance
(C) energy
(D) charge.
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D
10. Which of the following is not the same as watt?
(A) joule/sec
(B) amperes/volt
(C) amperes x volts
(D) ( amperes )2 x ohm.
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B
11. One kilowatt hour of electrical energy is the same as
(A) 36 x 105 watts
(B) 36 x 10s ergs
(C) 36 x 105 joules
(D) 36 x 105 B.T.U.
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C
12. An electric current of 5 A is same as
(A) 5 J / C
(B) 5 V / C
(C) 5 C / sec
(D) 5 w / sec.
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C
13. An electron of mass m kg and having a charge of e coulombs travels from rest through a potential difference of V
volts. Its kinetic energy will be (A) eV Joules
(B) meV Joules
(C)me / V Joules
(D)V / me Joules.
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A
14. The value of the following is given by 100 (kilo ampere ) x ( micro ampere ) 100 milli ampere * 10 ampere
(A) 0.001 A
(B) 0.1 A
(C) 1 A
(D) 10A.
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B
15. A circuit contains two un-equal resistances in parallel
(A) current is same in both
(B) large current flows in larger resistor
(C) potential difference across each is same
(D) smaller resistance has smaller conductance.
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C
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1.B ----- 2.D ----- 3.B ----- 4.B ----- 5.D ----- 6.C ----- 7.C ----- 8.B -----9.D -----10.B -----11.C ----- 12.C -----13.A ----14.B ----- 15.C
16.Conductance is expressed in terms of
(A) ohm / m
(B) m / ohm
(C) mho / m
(D) mho.
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17. Which of the following could be the value of resistivity of copper?
(A) 1.7 x 10-8 ohm-cm
(B). 1.7 x 10-6 ohm-cm
(C). 1.6 x 10-5 ohm-cm
(D). 1.7 x 10-4 ohm-cm
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18. A copper wire of length l and diameter d has potential difference V applied at its two ends. The drift velocity is v d.
If the diameter of wire is made d/3, then drift velocity becomes
(A) 9 vd
(B) vd / 9
(C)vd /3
(D)vd.
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19.Two resistances R1 and R2 give combined resistance of 4.5 ohms when in series and 1 ohm when in parallel. The
resistances are
(A)3 ohms and 6 ohms
(B)3 ohms and 9 ohms
(C)1.5 ohms and 3 ohms
(D)1.5 ohms and 0.5 ohms.
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20. We have three resistances of values 2 Ω, 3 Ω and 6 Ω. Which of the following combination will give an effective
resistance of 4 Ω?
(A) All the three resistances in parallel
(B) 2 Ω resistance in series with parallel combination of 3 Ω and 6 Ω resistance
(C) 3 Ω resistance in series with parallel combination of 2 Ω and 6 Ω resistance
(D) 6 Ω resistance in series with parallel combination of 2 Ω and 3 Ω resistance.
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21. Three equal resistors connected in series across a source of emf together dissipate 10 watts of power. What
would be the power dissipated in the same resistors when they are connected in parallel across the same source of
emf?
(A) 10 watts
(B) 30 watts
(C) 90 watts
(D) 270 watts.
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22.Current I in the figure is
(A)1.5A
(B)0.5A
(C)3.5A
(D)2.5A
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23.Four identical resistors are first connected in parallel and then in series. The resultant resistance of the first
combination to the second will be
(A) 1 / 16 times
(B) 1 / 4 times
(C) 4 times
(D) 16 times.
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24.Twelve wires of same length and same cross-section are connected in the form of a cube as shown in figure
below. If the resistance of each wire is R, then the effective resistance between P and Q will be
(A)R
(B) 5 / 6 R
(C) 3 / 4 R
(D) 4 / 3 R.
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25. When P = Power, V = Voltage, I = Current, R = Resistance and G = Conductance, which of the following relation
is incorrect?
(A) V = √ (PR)
(B). P= V2G
(C) G= P / I2
(D) I =√ (P / R)
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26.The unit of electrical conductivity is
(A) mho / metre
(B) mho / sq. m
(C) ohm / metre
(D) ohm / sq. m.
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27.Which of the following bulbs will have the least resistance ?
(A) 220 V, 60 W
(B) 220 V, 100 W
(C) 115 V, 60 W
(D) 115 V, 100 W.
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28.The ratio of the resistance of a 100 W, 220 V lamp to that of a 100 W, 110 V lamp will be nearly
(A) 4
(B)2
(C) 1 / 2
(D) 1 / 4
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29.The resistance of a 100 W, 200 V lamp is
(A) 100 ohm
(B) 200 ohm
(C) 400 ohm
(D) 1600 ohm.
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30.Two 1 kilo ohm, 1/2 W resistors are connected in series. Their combined resistance value and wattage will be
(A) 2 kΩ, 1/2 W
(B) 2 kΩ, 1 W
(C) 2 kΩ, 2 W
(D) l kΩ, 1/2 W.
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16.D -----17.B ----- 18.D ----- 19.C ----- 20.B ----- 21.C ----- 22.A ----- 23.A -----24.B -----25.C -----26.A ----- 27.D ----28.A -----29.C ----- 30.B
31.Which method can be used for absolute measurement of resistances ?
(A)Ohm's law method
(B)Wheatstone bridge method
(C)Releigh method
(D) Lortentz method.
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32.Three 3 ohm resistors are connected to form a triangle. What is the resistance between any two of the corners?
(A) 3 / 4 ohms
(B) 3 ohms
(C) 2 ohms
(D) 4/3 ohm.
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33.Five resistances are connected as shown in figure below. The equivalent resistance between the points A and B
will be
(A) 35 ohms
(B) 25 ohms
(C) 15 ohms
(D) 5 ohms.
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34.How many different combinations may be obtained with three resistors, each having the resistance R ?
(A) 3
(B) 4
(C) 5
(D) 6.
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35.A wire of 0.14 mm diameter and specific resistance 9.6 micro ohm-cm is 440 cm long. The resistance of the wire
will be
(A) 9.6 ohm
(B) 11.3 ohm
(C) 13.7 ohm
(D) 27.4 ohm.
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36.Ohm's law is not applicable to
(A) DC circuits
(B) high currents
(C) small resistors
(D) semi-conductors.
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37.A metal resistor has resistance of 10 ohm at 0°C and 11 ohms at 160°C, the temperature coefficient is
(A) 0.00625 / °C
(B) 0.0625 /°C
(C) 0.000625 /°C
(D) 0.625 /°C.
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Questions 38 to 40 refer to Figure given below.
Five resistances are connected as shown and the combination is connected to a 40 V supply.
38. Voltage between point P and Q will be
(A) 40 V
(B) 22.5 V
(C) 20 V
(D) 17.5 V.
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39.The current in 4 ohm resistor will be
(A) 2.1 A
(B) 2.7 A
(C) 3.0 A
(D) 3.5 A.
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40.Least current will flow through
(A) 25 ohm resistor
(B) 18 ohm resistor
(C) 10 ohm resistor
(D) 5 ohm resistor.
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41.Total power loss in the circuit is
(A)10W
(B) 50.2 W
(C) 205 W
(D) 410 W.
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42.A resistance of 5 ohms is further drawn so that its length becomes double. Its resistance will now be
(A) 5 ohms
(B) 7.5 ohms
(C) 10 ohms
(D) 20 ohms.
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43.Specific resistance of a substance is measured in
(A) ohms
(B) mhos
(C) ohm-cm
(D) cm/ohm.
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44.A wire of resistance R has it length and cross-section both doubled. Its resistance will become
(A) 4 R
(B)2 R
(C) R
(D) R / 4.
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45.Ohm's law is not applicable in all the following cases Except
(A) Electrolytes
(B) Arc lamps
(E) Insulators
(A) Vacuum ratio values.
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31.B ----- 32.C ----- 33.D ----- 34.B ----- 35.D ----- 36.D ----- 37.C ----- 38.B -----39.D -----40.A -----41.C ----- 42.D ----43.C -----44.C ----- 45.C
46.The element of electric heater is made of
(A) copper
(B) steel
(C) carbon
(D) nichrome.
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47. 5xl016 electrons pass across the section of a conductor in 1 minute 20 sec. The current flowing is
(A) 1mA
(B) 0.1 mA
(C) 0.01mA
(D) 10 mA.
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48.Which of the following figures represents the effect of temperature on resistance for copper ?
(A) figure A
(B) figure B
(C) figure C
(D) figure D.
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49.Three elements having conductance G1, G2 and G3 are connected in parallel. Their combined conductance will be
(A) 1/( 1/G1 + 1/G2 + 1/G3)
(B) (G1G2 + G2G3 + G3G1)/(G1 + G2 + G3)
(C) 1/(G1 + G2+ G3)
(D) G1 + G2 +G3
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Questions 50 to 53 refer to Figure given below:
50.The variation of resistance of iron and some alloys with temperature is shown in figure. The variation of carbon will
be represented by
(A) curve A
(B) curve B
(C) curve C
(D) curve D.
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51.Curves A and B represent the properties for materials which have
(A) low resistance
(B) low conductance
(C) negative resistance
(D) negative temperature coefficient.
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52.Which of the following has negative temperature coefficient ?
(A) Brass
(B) Mercury
(C) Electrolytes
(D) Silver.
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53.All of the following have negative temperature coefficient EXCEPT
(A) Paper
(B) Gold
(C) Rubber.
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54.For the circuit shown below the current I flowing through the circuit will be
(A)1 / 2 A
(B) 1 A
(C) 2 A
(D) 4 A.
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55.A cube of material of side 1 cm has a resistance of 0.002 ohm between its opposite faces. If the same volume of
the material has a length of 8 cm and a uniform cross-section, the resistance of this length will be
(A) 0.032 ohm
(B) 0.064 ohm
(C) 0.096 ohm
(D) 0.128 ohm.
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56.A standard 60 W bulb is in series with a room heater and connected across the mains. If the 60 W bulb is replaced
by 100 W bulb
(A) the heater output will increase
(B) the heater output will reduce
(C) the heater output will remains unaltered.
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57. Two aluminium conductors have equal length. The cross-sectional area of one conductor is four times that of the
other. If the conductor having smaller cross-sectional area has a resistance of 100 ohms the resistance of other
conductor will be
(A) 400 ohms
(B) 100 ohms
(C) 50 ohms
(D) 25 ohms.
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58.A nichrome wire used as heater coil has the resistance of 1 ohm/m. For a heater of 1000 W at 200 V, the length of
wire required will be
(A) 10 m
(B) 20 m
(C) 40 m
(D) 80 m.
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59.The hot resistance of a tungsten lamp is about 10 times the cold resistance. Accordingly, cold resistance of a 100
W, 200 V lamp will be (A) 4000 ohm
(B)400 ohm
(C)40 ohm
(D)4 ohm.
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60. Variable resistors are
(A)Wire wound resistors
(B)Thin film resistors
(C)Thick film resistors
(D)All of the above.
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46.D -----47. B ----- 48.A ----- 49. D ----- 50. B ----- 51.D ----- 52. C ----- 53. B ----- 54.C ----- 55. D ----- 56. A ----- 57. D
----- 58. C ----- 59. C ----- 60. A
61.Low resistance can be accurately measured by
(A) Kelvin bridge
(B )Wheat stone bridge
(C) Wein's bridge
(D) None of the above.
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62.A heating element of a hot plate on an electric cooking range draws 12 amperes from 240 V mains. How many
kWh of energy will be consumed in one hour and 15 minutes
(A) 1.2
(B) 3.2
(C) 6.0
(D) 7.2.
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63. Temperature coefficient of resistance is expressed in terms of
(A) ohms / ohms oC
(B) mhos / ohm oC
(C) mhos / oC
(D) ohms / oC.
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64. If R1 is the resistance of a coil of copper at t oC and RT is the resistance at T oC and also the resistance
temperature coefficient of copper per degree centrigrade at 0 oC is 1/234.45, then Rt/RT
(A) (1+t) / (1+T)
(B) (1+ 234.45t) / (1+234.45 T)
(C) (234.45 + t) / (234.45 + T)
(D) (234.45 + t2 ) / (234.45 + T 2).
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65. Resistivity is usually expressed in terms of
(A) mho
(B) ohm / oC
(C) ohms/cm-square
(D) ohms/cm-cube.
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66. Which material is expected to have least resistivity?
(A) Copper
(B) Lead
(C) Mercury
(D) Zinc.
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67. The shunt winding of a motor has a resistance of 85 ohm at 22 oC. When the motor runs at full load, its resistance
increases to 100 ohms. The resistance temperature coefficient of winding per 0oC is 0.004. The rise in temperature of
the winding will be nearly
(A) 20oC
(B) 50oC
(C)70oC
(D) 100oC.
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68. The resistance temperature coefficient is defined as
(A) increase in resistance per degree centigrade
(B) decrease in resistance per degree centigrade
(C) the ratio of increase in resistance per degree centigrade to the resistance at 0 oC
(D) the ratio of increases in resistance per degree centigrade to the rate of rise of resistance at 0 oC.
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69.Two coils connected in series have resistance of 600 ohm and 300 ohm and temperature coefficients of 0.1% and
0.4% respectively.The resistance of the combination at 50oC will be
(A) 1050 ohm
(B)1001 ohm
(C)1600 ohm
(D) 990 ohm.
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70. A 100 W, 200 V filament lamp has operating temperature of 2000 oC. The filament material has resistance
temperature coefficient of 0.005 at 0oC per oC. The current taken by the lamp at the instant of switching with 200 V
supply with filament temperature of 20oC will be
(A) 1 A
(B) 3 A
(C) 5 A
(D)10A.
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71. A fuse is always installed in a circuit is
(A) Series
(B) Parallel.
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72. The rating of fuse wire is expressed in terms of
(A) Ohms
(B) Mhos
(C) Amperes
(D) Watts.
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73. Which of the following material is not used as fuse material?
(A) Silver
(B) Copper
(C) Aluminium
(D) Carbon.
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Questions 74 to 78 refer to Figure below.
74. The voltage drop across the resistor 9 ohm will be
(A)18 V
(B) 12 V
(C) 9 V
(D) 6 V.
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75. The voltage drop will be least in which resistor ?
(A) 2 ohm
(B) 3 ohm
(C) 6 ohm
(D) 3 ohm and 6 ohm.
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61.A ----- 62. B ----- 63. A ----- 64. C ----- 65. D ----- 66. A ----- 67. C ----- 68. C ----- 69. D ----- 70. C ----- 71. A ----- 72.
C ----- 73. D ----- 74. A ----- 75.D
76. The current through 6 ohm resistor will be
(A) 1 A
(B) 2 A
(C) 3 A
(D) 4 A.
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77. The ratio of power dissipated in circuit ADB to that in circuit ABC will be
(A) 1
(B) 1.5
(C)0.67
(D) 2.
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78. Total power dissipated in the circuit is
(A) 80 W
(B)100 W
(C)120 W
(D) 150 W.
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79. The current carrying capacity of the fuse material depends on
(A) cross-sectional area
(B) length
(C) material
(D) all of the above.
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80. According to the fuse law, the current carrying capacity varies as
(A) diameter
(B) (diameter)3/2
(C) 1 / diameter
(D)1 / (diameter)2.
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Questions 81 to 83 refer to Figure given below.
81. For the circuit shown in Figure above, the value of current I will be
(A) 10A
(B) 15A
(C) 20A
(D) 25A.
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82. The combined resistance of the circuit is
(A) 10 ohms
(B) 5 ohms
(C) 4 ohms
(D) 2 ohms.
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83. Total power dissipated in the circuit is
(A) 2.5 kW
(B) 5.0 kW
(C) 7.5 kW
(D)10 kW.
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84. A 100 W bulb is connected in series with a room heater of 750 W. What will happen if the bulb is replaced by a
60W bulb?
(A) Heater output will increase
(B) Heater output will decrease
(C) Heater output will remain unchanged
(D) Bulb will not glow.
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85. An immersion rod heats a bucket of water in 15 minutes. In order that the water should boil in 10 minutes
(A) length of heating element of the rod should be increased
(B) length of heating element of the rod should be reduced
(C) supply voltage should be reduced
(D) heating element of larger diameter should be used.
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86. A lamp of 100 W at 200 V is supplied current at 100 volts. It will be equivalent to the lamp of
(A) 50 W
(B) 40 W
(C) 25 W
(D) 10 W.
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87. Two electric bulbs of 100 W, 200 V are put in series and the combination is supplied 100 V. The power
consumption of each bulb will be
(A) 100 / 2 W
(B) 100 / 4 W
(C) 100 / 8 W
(D) 100 / 16 W.
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Questions 88 to 91 refer to Figure given below.
88. Three lamps are in circuit as shown in Figure given above. The lamp of 100 W will have maximum brightness
when
(A) key k1 is closed, k2 is open and k3 is closed
(B) k1 is open, k2 is closed and k3 is open
(C) k1 is open, k2 is closed and k3 is also closed
(D) k1 is closed, k2 is open and k3 is also open.
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89. When switches k1 and k2 are open and k3 is closed
(A) 100 W lamp will glow brighter than 40 W lamp
(B) 40 W lamp will glow brighter than 100 W lamp
(C) Both will glow at their full brightness
(D) Both will glow at less than their full brightness.
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90. Which of the following statements is necessarily correct ?
(A) 40 W bulbs will always glow at full brightness
(B) 100 W bulb will always glows at full brightness
(C) Whatever be the position of keys, at least one 40 W bulb will always glow
(D) Whenever current flows through the circuit, 100 W bulb will always glow.
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76.C ----- 77.B ----- 78.C ----- 79.D ----- 80.B ----- 81.D ----- 82.C ----- 83. A -----84.B ----- 85.B ----- 86.C ----- 87.D ----88.B ----- 89.B ----- 90.D
Multiple Choice Questions of Electric Current and Ohm's Law (91-105):
91. 40 W bulb A will be least bright when
(A) only keys k1 and k2 are open
(B) only keys k2 is open
(C) only keys k3 is open
(D) all keys are closed.
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92. The power consumption of the circuit will be maximum when
(A) key k1 and k3 are closed and k2 is open
(B) key k1 is closed, k2 and k3 are open
(C) key k1 and k2 are closed and k3 is open
(D) all the keys are closed.
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93. Which of the following lamps will have least resistance at room temperature ?
(A) 200 W, 220 V
(B) 100 W, 220 V
(C) 60 W, 220 V
(D) 25 W, 220 V.
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94. Filaments of electric bulbs are usually made of
(A) Nichrome
(B) Tungsten
(C) Copper
(D) Carbon.
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95. The value of supply voltage for 500 W ,5 ohm load is
(A) 500 V
(B) 100V
(C) 50 V
(D) 10V.
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96. Which resistor will be physically larger in size ?
(A)10 ohm, 50 W
(B) 100 ohm, 10 W
(C) 1 kohm, 1 W
(D) 10 Mohm, 1/ 2 W.
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97. Four resistances R1 , R2, R3 and R4 are connected in series against 220 V supply. The resistances are such that
R1 > R2 > R3 > R4. The least power consumption will be in
(A) resistor R1
(B) resistor R2
(C) resistor R3
(D) resistor R4.
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98. 100 resistors of 100 ohms each arc connected in parallel. Their equivalent resistances will be
(A) 10,000 ohms
(B) 100 ohms
(C) 1 ohm
(D) 1/ 10000 ohm.
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99. For a fixed supply voltage the current flowing through a conductor will decrease when
(A) cross-sectional area of the conductor is increased
(B) length of the conductor is increased
(C) length of the conductor is reduced
(D) cross-sectional area is increased and length is decreased.
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100.When current flows through heater coil it glows but supply wiring does not glow because
(A) supply wiring is covered with insulation layer
(B) current through supply line flows at slower speed.
(C) supply wires arc made of superior material
(D) resistance of heater coil is more than that supply wires.
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101. The resistance of 1 meter length of 18 gauge copper wire is k ohm. The resistance of one metre length of 24
gauge copper wire will be
(A) k / 2 ohm
(B) 18 / 24 kohm
(C) k ohm
(D) more than k ohm.
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102. In the circuit shown below, the resistance R has a value that depends on the current Specially, R is 20 ohms
when the current I is zero, and the amount of increase in resistance is numerically equal to one-half the current. What
is the value of the current in the circuit?
(A) 8.33 A
(B) 10.0 A
(C) 12.5 A
(D) 50 A.
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103. If the length and diameter of a conductor is tripped, the resistance will increase approximately by
(A) 66 2/3 %
(B) 33 1/3 %
(C)-66 2/3 %
(D) -33 1/3 %.
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104. If the resistance of an incandescent light bulb changes as the voltage across the bulb is changed, which of the
following is true ?
(A) The internal inductance of the bulb causes this change
(B) The bulb is said to have a low ionization potential
(C) The bulb has constant resistance of the current through the bulb is changed
(D) The bulb is a type of non-linear resistance.
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105. Which method can be used for absolute measurement of resistance ?
(A) Ohm's law method
(B) Wheatstone bridge method
(C) Raleigh method
(D) Lortentz method.
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91.A ----- 92.A ----- 93.A ----- 94.B ----- 95.C ----- 96.A -----97.D ----- 98.C -----99.B ----- 100.D ----- 101.D ----- 102.B ---- 103.C ----- 104.D -----105.B
Multiple Choice Questions of Electric Current and Ohm's Law (106-120):
106. Two 1 kilo ohm, 1/2 W resistors are connected in series. Their combined resistance value and wattage will be
(A) 2 kohm, 1 / 2 W
(B) 2 kohm, 1 W
(C) 2kohm, 2 W
(D) 1 kohm, 1 / 2 W.
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107. The resistance of 100 W, 200 V tamp is
(A) 100 ohm
(B) 200 ohm
(C) 400 ohm
(D) 1600 ohm.
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108. A cylindrical wire is compressed in length by 10%. The percentage decrease in the resistance will be
(A) 16%
(B) 19%
(C) 20%
(D) 25%.
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109. Three resistance of 6 ohm each are connected as shown in Figure given below. The equivalent resistance
between X1 and X2 is
(A) 2 ohm
(B) 4 ohm
(C) 8 ohm
(D) 12 ohm.
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110. The unit of conductance is
(A) per ohm
(B) ohm/m
(C) mho/m
(D) mho.
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111. Ohm's law is not applicable in all the following cases except
(A) Electrolysis
(B) Arc lamps
(C) Insulators
(D) Vacuum radio valves.
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112. In which of the following circuits will the voltage source produce the most current?
(A) 10 V across a 10 ohm resistance
(B) 10 V across two 10 ohm resistance in series
(C) 10 V across two 10 ohm resistances in parallel
(D) 1000 V across Mohm resistance.
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113. A piece of sliver wire has a resistance of 1 ohm. A manganin wire has specific resistance 30 times that of silver.
The resistance of a manganin wire of one fourth length and one third diameter will be
(A) 6 / 5 ohm
(B) 1 ohm
(C) 67.5 ohm
(D) 86.75 ohm.
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114. A cube of material of side 1 cm has a resistance of 0.002 ohm between its opposite faces. If the same volume of
the material has a length of 8 cm and a uniform cross-section, the resistance of this length w ill be
(A) 0.032 ohm
(B) 0.064 ohm
(C) 0.096 ohm
(D) 0.128 ohm.
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115. The unit of conductivity is
(A) mho / m
(B) mho / sq. m
(C) ohm / m
(D) ohm / sq. m.
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116. For the circuit shown in the figure given below, the meter will read
(A) 1 A
(B) 5 A
(C) 10 A
(D) 25 A.
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117. For the circuit shown in figure given below, the reading in the ammeter A w ill be
(A) 2 A
(B) 0.5 A
(C) 0.4 A
(D) 0.2 A.
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118. According to Joule law heat produced by a current I while in flowing through a material of resistance R for a
length of time T, is proportional to (A) T only
(B) (RT)
(C) (IRT)
(D) (I2RT).
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119. In the color code for resistances black color represents the number (A) 0
(B) 1
(C) 2
(D) 3.
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120. In the color code white color represents the number
(A) 9
(B) 8
(C) 6
(D) 5.
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106.B -----107.C ----- 108.B ----- 109.A ----- 110.D ----- 111.C ----- 112.C -----113.C ----- 114.D ----- 115.A ----- 116. C ----117.C ----- 118.D -----119.A -----120.A
Multiple Choice Questions of Electric Current and Ohm's Law (121-135):
121. In the color code number 3 is represented by
(A) blue
(B) orange
(C) grey
(D) violet.
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122. The condition for the validity under Ohm's law is
(A) Temperature at positive end should be more than the temperature at negative end
(B) Current should be proportional to the size of resistance
(C) Resistance must be wire wound type
(D) Resistance must be uniform.
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123. In which figure the relationship between voltage V and current I is in accordance with Ohm's law ?
(A) Figure A
(B) Figure B
(C) Figure C
(D) Figure D.
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124. Production of heat due to current is related by which law
(A) Ohm's law
(B) Joule's law
(C) Kelvin's law
(D) Maxwell's law.
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125. A fixed resistance R is connected across a DC voltage source. If the voltage is gradually and uniformly
increased, the relationship between voltage and resistance is correctly represented in which group?
(A) Group A
(B) Group B
(C) Group C
(D) Group D.
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126. The maximum power that can be distributed in the load in the circuit shown in
(A) 3 watts
(B) 6 warts
(C) 6.75 watts
(D) 13.5 watts.
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127. A variable resistance R is connected across a source of voltage V. If the value of the resistance R is gradually
varied, the relationship between I and R will be represented by which curve ?
(A) Figure A
(B) Figure B
(C) Figure C
(D) Figure D.
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128. A 1 k, 1 W resistor can safely pass a current of
(A) 30mA
(B) 100mA
(C) 150 mA
(D) 500 mA.
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129. The resistance to the flow of current through a copper wire
(A) increases as the length of wire decrease
(B) decreases as the diameter of wire decreases
(C) increases as the length of wire increases
(D) decreases as the length of wire increases.
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130. For the same voltage, the ratio Resistance of 100 W lamp Resistance of 25 W lamp is:
(A) 1
(B) 4
(C)16
(D)1 / 4.
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131. The voltage drop across a resistor of 100 ohm is 10 volts. The wattage of the resistor must be
(A) 1 / 2 W
(B) 1 W
(C) 2 W
(D) 4 W.
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132. A 100 volt bulb has a resistance of 500 ohms. The number of hours it can work for every kWh of energy
consumed will be
(A) 20
(B) 40
(C) 50
(D) 60.
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133. A semi-conductor is
(A) one which conducts only half of applied voltage
(B) a material whose conductivity is same as between that of a conductor and an insulator
(C) a material made of alternate layers of conducting material and insulator
(D) a material which has conductivity a having average value of conductivity of metal and insulator.
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134. Two resistors R1 = 47 kohm, 1 W and R2 = 0 ohm, 1 W are connected in parallel. The combined value will be
(A) 47 kohm, 1 W
(B) 47 kohm, 2W
(C) 47 kohm, 1 / 2 W
(D) 0 kohm, 1W.
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135. A rheostat differs from potentiometer in the respect that
(A) rheostat has large number of turns
(B) rheostat offers larger number of tappings
(C) rheostat has lower wattage rating
(D) rheostat has higher wattage ratings.
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121.B -----122.D ----- 123.B ----- 124.B ----- 125.A ----- 126.C -----127.B -----128.A ----- 129.C ----- 130.D ----- 131.B ---- 132.C ----- 133.B -----134.D -----135.D
Multiple Choice Questions of Electric Current and Ohm's Law (136-150):
136. The equivalent resistance at the points X1 and X2 in the circuit shown below
(A) 60 ohm
(B) 40ohm
(C) 80 ohm
(D) 20ohm.
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137. For the same electrical resistance, the weight of aluminium conductor as compared to copper conductor of
identical cross-section is (A) 85%
(B) 50%
(C) 20%
(D) 120%.
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138. A drawn wire of resistance 25 ohm is further drawn so that its diameter becomes one fifth. Its resistance will now
be
(A) 625 ohm
(B) 125 ohm
(C) 25 ohm
(D) 1 ohm.
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139. Which of the following has negative coefficient of resistance?
(A) Wire wound resistor
(B) Metals
(C) Non-metals
(D) Thermistor.
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140. The current at a given point in a certain circuit may be written as a function of time t, as i ( t ) = -3 + t. The total
charge passing a point between t = 99 and t = 102 sec will be
(A) 112 coulombs
(B) 242.5 coulombs
(C) 292.5 coulombs
(D) 345.6 coulombs.
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Questions 141 and 142 refer to the data given below:
A certain passive circuit element has the characteristic that the instantaneous voltage across it is always exactly three
times the cube of the instantaneous current through it
141. The power being dissipated when i = 0.1 A will be
(A) 3 W
(B) 0.3 W
(C) 3 x 10-3 W
(D) 3 x 10 -4 W.
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142. The power being dissipated when i = 10 A will be
(A) 3 W
(B) 30 W
(C) 3 kW
(D) 30 kW.
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143. A resistor has the value of 30 kohm and the current in it is measured to be 0.5 mA. The conductance is
(A) 15
(B) 30000
(C) 3.33 x 10-5
(D) 3.33 x 10-3
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144. In the above problem, the terminal voltage must be
(A) 15 mV
(B) 1.5 V
(C) 15 V
(D) 150 V.
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145. The charge of an electron is known to be 1.6 x 10-19C. How many electron does not 1 make it C of charge ?
(A) one
(B) one million
(C) 6.2 x 1018
(D) 1.6 x 10-19.
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146. The current entering the terminal of an element is given by the equation i ( t ) = 10 6 t2 - 107t A. The total charge
flowing, into the element between t = 1 s and t = 2 s will be nearly
(A) 2.2 x 10-6C
(B) 1.6 x 10 -6C
(C) 0.6 x 10-8C
(D) 0.6 x 10 -10C.
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147. An electron in a vacuum tube is observed to lose 1.6 x 10 -20 J of energy in moving from point A to point B. The
voltage of point B with respect of point A is
(A) - 1 V
(B) + 1 V
(C)- 0.1V
(D) + 0.1 V.
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148. In electronic micro-circuits, a resistor may be fabricated from a constant-thickness layer of semi-conductor
material with conductor connections at the edges as shown in Figure given below. If the resistor shown has
resistance R, then a similar resistor 0.2 millimeter by 0.2 millimeter has a resistance of
(A) 4 R
(B) 2 R
(C) R
(D) R / 2
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149. Certain substances lose their electrical resistance completely at finite low temperatures. Such substances are
called
(A) dielectrics
(B) super-conductors
(C) semi conductors
(D) perfect conductors.
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150. We have three resistances each of 1 ohm. How many different values of resistance can be obtained by different
series-parallel combinations if all the three resistances are to remain in the circuit?
(A) Three
(B) Four
(C) Five
(D) Six.
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136.B ----- 137.B ----- 138.A ----- 139.D ----- 140.C ----- 141.D ----- 142.D -----143.C ----- 144.C ----- 145.C ----- 146.A ---- 147.C ----- 148.C ----- 149.B ----- 150.B
Multiple Choice Questions of Electric Current and Ohm's Law (151-165):
151. A resistor has the value of 3 kohm and the current through it is measured to be 0.3 mA. The conductance is
(A) 30000 mho
(B) 30 mho
(C) 0.33 milli mho
(D) 30 micro mho.
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152. Resistance between X1 and X2 is
(A) 10 ohm
(B) greater than 10 ohm
(C) 0
(D) less than 10 ohm.
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153. When checked with an ohm meter an open resistor reads
(A) zero
(B) high but within tolerance
(C) low but not zero
(D) infinite.
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154. A current of 1 mA flows through a 1 Mohm, 2 W carbon resistor. The power dissipated as heat in the resistor will
be
(A) 2 W
(B) 1 W
(C) 0.5W
(D) 0.1W.
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155. Which of the following carbon coded resistor has value of 10 kohm with 20% tolerance?
(A) Red, red, green and silver stripes
(B) Yellow, violet, yellow and silver stripes
(C) Orange, orange, black and gold stripes
(D) Brown, black, orange and no tolerance band.
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156. A carbon resistor has to meet the following requirements IR drop: 5 V, Current: 100 mA, Safety factor for power
dissipation : 2. Which of the following resistors will be suitable ?
(A) 5 ohm, 10 W
(B) 0.5 ohm, 100 W
(C) 5 ohm, 10 W
(D) 50 ohm, 1 W.
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157. A 10 ohm resistor with a 10 W power rating is expected to be a
(A) carbon resistor
(B) wire wound resistor
(C) either carbon or wire wound resistor
(D) neither carbon nor wire wound resistor.
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158. Two 10 kohm, 5 W resistors in parallel have equivalent resistances of 5 kohm and power rating of
(A) 2.5 W
(B) 5 W
(C) 10 W
(D) 25 W.
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159. Which of the following is typical resistance and power dissipation value for a wire wound resistor?
(A) 1Mohm, 1 / 3 W
(B) 50kohm, 1 / 2 W
(C) 500 ohm, 1 W
(D) 10 ohm, 50 W.
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160. A 100 kohm resistor with a 1 W power rating is likely to be a
(A) carbon resistor
(B) wire wound resistor
(C) either carbon or wire wound resistor
(D) neither carbon nor wire wound resistor.
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161. Two 5 kohm, 5 W resistors in series have equivalent resistance of 10 kohm with power rating of
(A) 2.5 W
(B) 5 W
(C)10W
(D) 25 W.
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162. Which of the following are typical resistance and power-dissipation values for a carbon- composition resistor ?
(A) 10,000 ohm, 10 W
(B) 1000,000 ohm, 1 W
(C) 5000 ohm, 100 W
(D) 10 ohm, 50 W.
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163. A resistor is to be connected across a 45 V battery to provide 1 mA of current. The required resistance with a
suitable wattage rating is
(A) 45 ohm, 10 W
(B) 4.5 ohm, 2 W
(C) 450 kohm, 2 W
(D) 45 kohm, 1/4 W.
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164. In the circuit shown below, heat produced in 5 ohm resistance is 10 cal/sec. Heat developed in 4ohm is
(A) 1 cal/sec
(B) 2 cal/sec
(C) 3 cal/sec
(D) 4 cal/sec.
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165. For a carbon-composition resistor color-coded with yellow, violet, orange and silver stripes from left to right, the
value of resistance and tolerance are
(A) 470 ohm ± 10%
(B) 47ohm ± 10%
(C) 740 ohm ± 50%
(D) 74 ohm ± 5%.
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151. C -----152.C -----153.D -----154.B ----- 155.D ----- 156.D ----- 157.B ----- 158.C ----- 159.D -----160.A -----161.C ---- 162.B ----- 163. D----- 164.B ----- 165.B
Multiple Choice Questions of Electric Current and Ohm's Law (166-180):
166. For a carbon-composition resistor color coded with green, black, gold and silver stripes from left to right, the
resistance and tolerance are (A) 50 ohm ± 10%
(B) 5 ohm ± 5%
(C) 5 ohm ± 10%
(D) 0.5 ohm ± 5%.
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167. A resistor with the color coded value of 1000 ohms and ± 10% tolerance can have an actual resistance between
(A) 990 ohm and 1010 ohm
(B)900 ohm and 1100 ohm
(C)1000 ohm and 1100 ohm
(D)900 ohm and 1000 ohm.
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168. For carbon resistors what is the color for 5?
(A) Green
(B) Black
(C) Orange
(D) Gray.
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169. For carbon resistors, darker colour generally have values close to (A) 1
(B) 5
(C) 8
(D) 9.
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170. In a carbon resistor in case fourth stripe is not present, it can be concluded that
(A) the resistor is highly accurate
(B) the resistor is defective
(C) the resistor does not contain carbon
(D) the tolerance limit is ± 20 %.
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171. The four stripes of a resistor are yellow-violet-orange-gold. The value of resistor should be
(A) 470 ohms ± 5 %
(B) 47 kilo ohm ± 5%
(C) 47 mega ohms ± 5%
(D) 4700 ohms ± 10%.
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172. The tolerance for silver stripe is
(A)+5%
(B)+ 10%
(C)± 5%
(D)± 10%.
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173. Which of the following can have positive or negative charge?
(A) Electron
(B) iron
(C) Hole
(D) Neutron.
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174. Which of the following parallel resistances will have the highest value of equivalent resistance?
(A) 10 kohm and 25 kohm
(B) 1 kohm, 2 kohm and 3 kohm
(C) Two 500 kohm resistors
(D) Four 40 kohm and two 10 kohm resistors.
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175. In series as well as parallel circuits the equivalent (total) value of certain parameter is given by X = X 1 + X2 +
X3 + X4 + ... The parameter X could be
(A) resistance
(B) current
(C) voltage
(D) power.
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176. The resistance of a 150-scale voltmeter is 12000 ohms. The power consumed by the voltmeter when it is
connected across a 125 volt circuit, will be nearly
(A) 0.0013 W
(B) 0.013 W
(C) 0.13 W
(D) 1.3 W.
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177. Materials having electrical conductivity much less than most of the metals but much greater than that of typical
insulators, are known as
(A) thermistors
(B) varistors
(C) semi-conductors
(D) variable resistors.
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178. Match the following :
Column 1
Copper
Salt Solution
Germanium
Ferronickel alloys
Column 2
Resistors
Electrolytic Conductor
Good Conductor
Semi-Conductors
(A) a-(i), b-(ii), c-(iii), d(iv)
(B) a-(ii), b(iii), c-(iv), d-(i)
(C) a-(iiii),b-(i), c-(ii), d-(i)
(D) a-(iii), b-(ii) c-(iv), d-(i).
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179. In the circuit shown below, the current I is
(A)1 / 45 A
(B)1 / 15 A
(C)1 / 10 A
(D)1 / 5 A.
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180. In a nickel-cadmium-alkali cell the electrolyte is
(A) sulphur acid
(B) potassium hydroxide
(C) zinc chloride
(D) ammonium chloride.
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166. C -----167.B -----168.A -----169.A ----- 170.D ----- 171.B ----- 172.D ----- 173.B ----- 174.C -----175.D -----176.D ---- 177.C ----- 178. D----- 179.C ----- 180.B
Multiple Choice Questions of Electric Current and Ohm's Law (181-200):
181. Which value of resistance P shown in the circuit will allow 1080 Watts to be dissipated
(A) 19.5 ohms
(B) 14.5 ohms
(C) 9.75 ohms
(D) 5.55 ohms.
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182. There are 8.5 x 1028 free electrons in one cubic metre of copper. When the copper conductor is worked at 155
A/cm2 the velocity of the axial drift will be
(A) 1.14 x 10-6 m/s
(B) 1.14 x 10-5 m/s
(C) 1.14 x 10-4 m/s
(D) 1.14 x 10-3 m/s.
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183. Two batteries have an open-circuit voltage of 12.8 volts each and an internal resistance of 0.08 ohms. The short
circuit current of two batteries connected in parallel will be
(A) 80 A
(B) 120 A
(C) 160 A
(D) 320 A.
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Questions 184 and 185 refer to data given below:
A radiator element supplied at 240 V dissipates 2.4 MJ in 20 minutes.
184.The power dissipated in the elements is
(A) 2000 W
(B) 1000 W
(C) 500 W
(D) 200 W.
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185.The resistance of the element is
(A) 68 ohms
(B) 28.8 ohms
(C) 14.4 ohms
(D) 7.2 ohms.
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Questions 186 to 188 refer to data given below :
Two loads X and Y, are connected in parallel to a 115 V supply. Load X takes 35 watts and the total current is 2.6 A.
186.The resistance of X is
(A) 379 ohms
(B) 291 ohms
(C) 233 ohms
(D) 190 ohms.
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187.The resistance of Y is
(A) 200 ohms
(B) 100 ohms
(C) 50 ohms
(D) 20 ohms.
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188.The power absorbed by Y is
(A) 528 W
(B) 264 W
(C) 132 W
(D) 66 W.
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Questions 189 and 190 refer to data given below:
A source whose no-load voltage is 220 V delivers 20 watts to a load when the current is 0.4 A.
189. The internal resistance of the source is
(A) 10 ohms
(B) 20 ohms
(C) 50 ohms
(D) 100 ohms.
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190.The maximum power that can be delivered by the source is
(A) 51 W
(B) 102 W
(C) 152 W
(D) 242 W.
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191. All good conductors have high
(A) resistance
(B) electrical conductivity
(C) electrical and thermal conductivity
(D) conductance.
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192. A light dependent resistor is basically a
(A) power resistor
(B) non-metallic resistor
(C) carbon resistor
(D) variable resistor.
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193. Voltage dependent resistors are usually made from
(A) graphite
(B) charcoal
(C) silicon carbide
(D) nichrome.
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194. The power rating of a 470 ohm resistor carrying a current of 40 mA should be
(A)1 / 4 W
(B)1 / 2 W
(C) 1 W
(D) 2 W.
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195. Resistance across A and B in the circuit shown below is
(A) R
(B) 3 R
(C) 4 R
(D) 5 R.
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196. Voltage dependent resistors are used
(A) as current stabilizers
(B) as heating elements
(C) for inductive circuits
(D) to suppress surges.
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197. Metals approach super-conductivity conditions
(A) near absolute zero temperature
(B) near critical temperature
(C) at triple point
(D) under the conditions of high temperature and pressure.
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198. In which of the following the resistance decreases with rise in temperature ?
(A) LDR
(B) NTC thermistors
(C) Nichrome conductors
(D) ACSR conductors.
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199. The equivalent resistance of 2N branches in parallel, each having resistance N/2 ohms will be
(A) 4 ohms
(B) 2 ohms
(C) 1 ohm
(D) 1 / 4 ohm.
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200. Equivalent Resistance between X and Y is
(A)50 ohm
(B) 75 ohm
(C)275 ohm
(D)none of the above.
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181. C -----182.C -----183.D -----184.A ----- 185.B ----- 186.A ----- 187.C ----- 188.B ----- 189.C -----190.D -----191.D ---- 192.D ----- 193. C----- 194.C ----- 195.A ----- 196.D ----- 197.A ----- 198.B ----- 199.D ----- 200.D