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Electronics self test answers
Electronics m (‫ ةينقتلا نيطسلف ةعماج‬- ‫)يروضخ‬
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ELECTRONIC DEVICES – "SELF-TEST" ANSWERS
By: Rand Al-asa'd
Chapter 1: Introduction to Electronics
1. Every known element has
(a) the same type of atoms
(b) the same number of atoms
(c) a unique type of atom
(d) several different types of atoms
Answer: Option C
2. An atom consists of
(a) one nucleus and only one electron
(b) one nucleus and one or more electrons
(c) protons, electrons, and neutrons
(d) answers (b) and (c)
Answer: Option D
3. The nucleus of an atom is made up of
(a) protons and neutrons
(b) electrons
(c) electrons and protons
(d) electrons and neutrons
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Answer: Option A
4. Valence electrons are
(a) in the closest orbit to the nucleus
(b) in the most distant orbit from the nucleus
(c) in various orbits around the nucleus
(d) not associated with a particular atom
Answer: Option B
5. A positive ion is formed when
(a) a valence electron breaks away from the atom
(b) there are more holes than electrons in the outer orbit
(c) two atoms bond together
(d) an atom gains an extra valence electron
Answer: Option A
6. The most widely used semiconductive material in electronic devices is
(a) germanium
(b) carbon
(c) copper
(d) silicon
Answer: Option D
7. The difference between an insulator and a semiconductor is
(a) a wider energy gap between the valence band and the conduction ban
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(b) the number of free electrons
(c) the atomic structure
(d) answers(a), (b), and (c)
Answer: Option D
8. The energy band in which free electrons exist is the
(a) first band
(b) second band
(c) conduction band
(d) valence band
Answer: Option C
9. In a semiconductor crystal, the atoms are held together by
(a) the interaction of valence electrons
(b) forces of attraction
(c) covalent bonds
(d) answers (a), (b), and (c)
Answer: Option D
10. The atomic number of silicon is
(a) 8
(b) 2
(c) 4
(d) 14
Answer: Option D
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11. The atomic number of germanium is
(a) 8
(b) 2
(c) 4
(d) 32
Answer: Option D
12. The valence shell in a silicon atom has the number designation of
(a) 0
(b) 1
(c) 2
(d) 3
Answer: Option D
13. Each atom in a silicon crystal has
(a) four valence electrons
(b) four conduction electrons
(c) eight valence electrons, four of its own and four shared
(d) no valence electrons because all are shared with other atoms
Answer: Option C
14. Electron-hole pairs are produced by
(a) recombination
(b) thermal energy
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(c) ionization
(d) doping
Answer: Option B
15. Recombination is when
(a) an electron falls into a hole
(b) and a negative ion bond together
(c) a valence electron becomes a conduction electron
(d) a crystal is formed
Answer: Option A
16. The current in a semiconductor is produced by
(a) electrons only
(b) holes only
(c) negative ions
(d) both electrons and holes
Answer: Option D
17. In an intrinsic semiconductor,
(a) there are no free electrons
(b) the free electrons are thermally produced
(c) there are only holes
(d) there are as many electrons as there are holes
(e) answers (b) and (d)
Answer: Option E
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18. The process of adding an impurity to an intrinsic semiconductor is called
(a) doping
(b) recombination
(c) atomic modification
(d) ionization
Answer: Option A
19. A trivalent impurity is added to silicon to create
(a) germanium
(b) a p-type semiconductor
(c) an n-type semiconductor
(d) a depletion region
Answer: Option B
20. The purpose of a pentavalent impurity is to
(a) reduce the conductivity of silicon
(b) increase the number of holes
(c) increase the number of free electrons
(d) create minority carriers
Answer: Option C
21.The majority carriers in an n-type semiconductor are
(a) holes
(b) valence electrons
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(c) conduction electrons
(d) protons
Answer: Option C
22. Holes in an n-type semiconductor are
(a) minority carriers that are thermally produced
(b) minority carriers that are produced by doping
(c) majority carriers that are thermally produce
(d) majority carriers that are produced by doping
Answer: Option A
23.A pn junction is formed by
(a) the recombination of electrons and holes
(b) ionization
(c) the boundary of a p-type and an n-type material
(d) the collision of a proton and a neutron
Answer: Option C
24. The depletion region is created by
(a) ionization
(b) diffusion
(c) recombination
(d) answers (a), (b), and (c)
Answer: Option D
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25. The depletion region consists of
(a) nothing but minority carriers
(b) positive and negative ions
(c) no majority carriers
(d) answers(b) and (c)
Answer: Option D
Chapter 2: Diodes and Applications
1. The term bias means
(a) the ratio majority carriers to minority carriers
(b) the amount of current across a diode
(c) a dc voltage is applied to control the operation of a device
(d) neither (c), (c), nor (c)
Answer: Option C
2. To forward-bias a diode,
(a) an external voltage is applied that is positive at the anode and negative at the
cathode
(b) an external voltage is applied that is negative at the anode and positive at the
cathode
(c) an external voltage is applied that is positive at the p region and positive at the n
region
(d) answers (a) and (c)
Answer: Option D
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3. When a diode is forward-biased,
(a) the only current is hole current
(b) the only current is electron current
(c) the only current is produced by majority carriers
(d) the current is produced both holes and electrons
Answer: Option D
4. Although current is blocked in reverse bias,
(a) there is some current due to majority carriers
(b) there is a very small current due to minority carriers
(c) there is an avalanche current
Answer: Option B
5. For a silicon diode, the value of the forward-bias voltage typically
(a) must be greater than 0.3 V
(b) must be greater than 0.7 V
(c) depends on the width of the depletion region
(d) depends on the concentration of majority carriers
Answer: Option B
6. When forward-biased, a diode
(a) blocks current
(b) conducts current
(c) has high resistance
(d) drops a large voltage
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Answer: Option B
7. A diode is normally operated in
(a) reverse breakdown
(b) the forward-bias region
(c) the reverse-bias region
(d) either (b) or (c)
Answer: Option D
8. The dynamic resistance can be important when a diode is
(a) reverse-biased
(b) forward-biased
(c) in reverse breakdown
(d) unbiased
Answer: Option B
9. The V-I curve for a diode shows
(a) the voltage across the diode for a given current
(b) the amount of current for a given bias voltage
(c) the power dissipation
(d) none of these
Answer: Option A
10. Ideally, a diode can be represented by a
(a) voltage source
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(b) resistance
(c) switch
(d) all of these
Answer: Option C
11. In the practical diode model,
(a) the barrier potential is taken into account
(b) the forward dynamic resistance is taken into account
(c) none of these
(d) both (a) and (b)
Answer: Option A
12. In the complete diode model,
(a) the barrier potential is taken into account
(b) the forward dynamic resistance is taken into account
(c) the reverse resistance is taken into account
(d) all of these
Answer: Option D
13. The average value of a half-wave rectified voltage with a peak value of 200 V is
(a) 63.7 V
(b) 127.2 V
(c) 141 V
(d) 0 V
Answer: Option A
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14. When a 60 Hz sinusoidal voltage is applied to the input of a half-wave rectifier,
the output frequency is
(a) 120 Hz
(b) 30 Hz
(c) 60 Hz
(d) 0 Hz
Answer: Option C
15. The peak value of the input to a half-wave rectifier is 10 V. The approximate
peak value of the output is
(a) 10 V
(b) 3.18 V
(c) 10.7 V
(d) 9.3 V
Answer: Option D
16. For the circuit in the previous question, the diode must be able to withstand a
reverse voltage of
(a) 10 V
(b) 5 V
(c) 20 V
(d) 3.18 V
Answer: Option A
17. The average value of a full-wave rectified voltage with a peak value of 75 V is
(a) 53 V
(b) 47.8 V
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(c) 37.5 V
(d) 23.9 V
Answer: Option B
18. When a 60 Hz sinusoidal voltage is applied to the input of a full-wave rectifier,
the output frequency is
(a) 120 Hz
(b) 60 Hz
(c) 240 Hz
(d) 0 Hz
Answer: Option A
19. The total secondary voltage in a center-tapped full-wave rectifier is 125 V rms.
neglecting the diode drop, the rms output voltage is
(a) 125 V
(b) 177 V
(c) 100 V
(d) 62.5 V
Answer: Option D
20. When the peak output voltage is 100 V, the PIV for each diode in a centertapped full-wave rectifier is (neglecting the diode drop)
(a) 100 V
(b) 200 V
(c) 141 V
(d) 50 V
Answer: Option B
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21. When the rms output voltage of a bridge full-wave rectifier is 20 V, the peak
inverse voltage across the diodes is (neglecting the diode drop)
(a) 20 V
(b) 40 V
(c) 28.3 V
(d) 56.6 V
Answer: Option C
22. The ideal dc output voltage of a capacitor-input filter is equal to
(a) the peak value of the rectified voltage
(b) the average value of the rectified voltage
(c) the rms value of the rectified voltage
Answer: Option A
23. A certain power-supply filter produces an output with a dc value of 20 V. The
ripple factor is
(a) 0.05
(b) 0.005
(c) 0.00005
(d) 0.02
Answer: Option B
24. A 60 V peak full-wave rectified voltage is applied to a capacitor-input filter. If f =
120 Hz, RL= 10 kΩ, and C = 10µF, the ripple voltage is
(a) 0.6 V
(b) 6 mV
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(c) 5.0 V
(d) 2.88 V
Answer: Option C
25. If the load resistance of a capacitor-filtered full-wave rectifier is reduced, the
ripple voltage
(a) increases
(b) decreases
(c) is not affected
(d) has a different frequency
Answer: Option A
26. Line regulation is determined by
(a) load current
(b) zener current and load current
(c) changes in load resistance and output voltage
(d) changes in output voltage and input voltage
Answer: Option D
27. Load regulation is determined by
(a) changes in load current and input voltage
(b) changes in load current and output voltage
(c) changes in load resistance and input voltage
(d) changes in zener current and load current
Answer: Option B
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28. A 10 V peak-to-peak sinusoidal voltage is applied across a silicon diode and
series resistor. The maximum voltage across the diode is
(a) 9.3 V
(b) 5 V
(c) 0.7 V
(d) 10 V
(e) 4.3 V
Answer: Option C
29. In a certain biased limiter, the bias voltage is 5 V and the input is a 10 V peak
sine wave. If the positive terminal of the bias voltage is connected to the cathode of
the diode, the maximum voltage at the anode is
(a) 10 V
(b) 5 V
(c) 5.7 V
(d) 0.7 V
Answer: Option C
30. In a certain positive clamper circuit, a 120 V rms sine wave is applied to the
input. The dc value of the output is
(a)119.3 V
(b) 169 V
(c) 60 V
(d) 75.6 V
Answer: Option B
31. The input of a voltage doubler is 120 V rms. The peak-to-peak output is
approximately
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(a) 240 V
(b) 60 V
(c) 167 V
(d) 339 V
Answer: Option A
32. If the input voltage to a voltage tripler has an rms value of 12 V, the dc output
voltage is approximately
(a) 36 V
(b) 50.9 V
(c) 33.9 V
(d) 32.4 V
Answer: Option B
33. When a silicon diode is working properly in forward-bias, a DMM in the diode test
position will indicate
(a) 0 V
(b) OL
(c) approximately 0.7 V
(d) approximately 0.3 V
Answer: Option C
34. When a silicon diode is open, a DMM will generate indicate
(a) 0 V
(b) OL
(c) approximately 0.7 V
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(d) approximately 0.3V
Answer: Option B
35. In a rectifier circuit, if the secondary winding in the transformer opens, the output
is
(a) 0 V
(b) 120 V
(c) less than it should be
(d) unaffected
Answer: Option A
36. If one of the diodes in a bridge full-wave rectifier opens, the output is
(a) 0 V
(b) one-fourth the amplitude of the input voltage
(c) a half-wave rectified voltage
(d) a 120 Hz voltage
Answer: Option C
37. If you are checking a 60 Hz full-wave bridge rectifier and observe that the output
has a 60 Hz ripple,
(a) the circuit is working properly
(b) there is an open diode
(c) the transformer secondary is shorted
(d) the filter capacitor is leaky
Answer: Option B
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Chapter 3: Special-Purpose Diodes
1. The cathode of a zener diode in a voltage regulator is normally
(a) more positive than the anode
(b) more negative than the anode
(c) at +0.7 V
(d) grounded
Answer: Option A
2. If a certain zener diode has a zener voltage of 3.6 V, it operates in
(a) regulated breakdown
(b) zener breakdown
(c) forward conduction
(d) avalanche breakdown
Answer: Option B
3. For a certain 12 V zener diode, 10 mA change in zener current produces a 0.1 V
change in zener voltage. The zener impedance for this current range is
(a) 1Ω
(b) 100Ω
(c) 10Ω
(d) 0.1Ω
Answer: Option C
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4. The datasheet for particular zener gives Vz = 10V at Iz = 500 mA. Zz for these
condition is
(a) 50 Ω
(b) 20 Ω
(c) 10 Ω
(d) unknown
Answer: Option B
5. A no-load condition means that
(a) the load has infinite resistance
(b) the load has zero resistance
(c) the output terminals are open
(d) answers(a) and (c)
Answer: Option D
6. A varactor diode exhibits
(a) a variable capacitance that depends on reverse voltage
(b) a variable resistance that depends on reverse voltage
(c) a variable capacitance that depends on forward current
(d) a constant capacitance over a range of reverse voltages
Answer: Option A
7. An LED
(a) emits light when reverse-biased
(b) senses light when reverse-biased
(c) emits light when forward-biased
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(d) acts as a variable resistance
Answer: Option C
8. Compared to a visible red LED, an infrared LED
(a) produces light with shorter wavelengths
(b) produces light of all wavelengths
(c) produces only one color of light
(d) produces light with longer wavelengths
Answer: Option D
9. Compared to incandescent bulbs, high-intensity LEDs
(a) are brighter
(b) have a much longer life
(c) use less power
(d) all of the above
Answer: Option D
10. An OLED differs from a conventional LED in that it
(a) requires no bias voltage
(b) as layers of organic material in the place of a pn junction
(c) can be implemented using an inkjet printing process
(d) both (b) and (c)
Answer: Option D
11. An infrared LED is optically coupled to a photodiode. When the LED is turned off,
the reading on an ammeter in series with the reverse-biased photodiode will
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(a) not change
(b) decrease
(c) increase
(d) fluctuate
Answer: Option B
12. The internal resistance of a photodiode
(a) increases with light intensity when reverse-biased
(b) decreases with light intensity when reverse-biased
(c) increases with light intensity when forward-biased
(d) decreases with light intensity when forward-biased
Answer: Option B
13. A laser diode produces
(a) incoherent light
(b) coherent light
(c) monochromatic light
(d) both (b) and (c)
Answer: Option D
14. A diode that has a negative resistance characteristic is the
(a) Schottky diode
(b) tunnel diode
(c) laser diode
(d) hot-carrier diode
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Answer: Option B
15. In order for a system to function properly, the various types of circuits that make
up the system must be
(a) properly biased
(b) properly connected
(c) properly interfaced
(d) all of the above
(e) answers (a) and (b)
Answer: Option E
Chapter 4: Bipolar Junction Transistors
1. The three terminals of a bipolar junction transistor are called
(a) p, n, p
(b) n, p, n
(c) input, output, ground
(d) base, emitter, collector
Answer: Option D
2. In a pnp transistor, the p region are
(a) base and emitter
(b) base and collector
(c) emitter and collector
Answer: Option C
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3. For operation as an amplifier, the base of an npn transistor must be
(a) positive with respect to the emitter
(b) positive with respect to the collector
(c) negative with respect to the emitter
(d) 0V
Answer: Option A
4. The emitter current is always
(a) greater than the base current
(b) less than the collector current
(c) greater than the collector current
(d) answers (a) and (c)
Answer: Option D
5. The βdc of a transistor is its
(a) current gain
(b) voltage gain
(c) power gain
(d) internal resistance
Answer: Option A
6. If Ic is 50 times larger than Ib, then βdc is
(a) 0.02
(b) 100
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(c) 50
(d) 500
Answer: Option C
7. The approximate voltage across the forward-biased base-emitter junction of
silicon BJT is
(a) 0V
(b) 0.7
(c) 0.3
(d) VBB
Answer: Option B
8. The bias condition for a transistor to be used as a linear amplifier is called
(a) forward-reverse
(b) forward-forward
(c) reverse-reverse
(d) collector bias
Answer: Option A
9. If the output of a transistor amplifier is 5V rms and the input is 100mV rms, the
voltage gain is
(a) 5
(b) 500
(c) 50
(d) 100
Answer: Option C
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10. When a lowercase r’ is used in relation to a transistor, it refers to
(a) a low resistance
(b) a wire resistance
(c) an internal ac resistance
(d) a source resistance
Answer: Option C
11. In a given transistor amplifier, Rc= 2.2 kΩ and r’e =20Ω, the voltage gain is
(a) 2.2
(b) 110
(c) 20
(d) 44
Answer: Option B
12. When operated in cutoff and saturation, the transistor acts like a
(a) linear amplifier
(b) switch
(c) variable capacitor
(d) variable resistor
Answer: Option B
13. In cutoff, Vce is
(a) 0V
(b) minimum
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(c) maximum
(d) equal to Vcc
(e) answers (a) and (b)
(f) answers (c) and (d)
Answer: Option F
14. In saturation, Vce is
(a) 0.7V
(b) equal to Vcc
(c) minimum
(d) maximum
Answer: Option C
15. To saturate a BJT,
(a) Ib= Ic(sat)
(b) Ib>Ic(sat)/βdc
(c) Vcc must be at least 10V
(d) the emitter must be grounded
Answer: Option B
16. Once in saturation, a further increase in base current will
(a) cause the collector current to increase
(b) not affect the collector current
(c) cause the collector current to decrease
(d) turn the transistor off
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Answer: Option B
17. In a phototransistor, base current is
(a) set by a bias voltage
(b) directly proportional to light intensity
(c) inversely proportional to light intensity
(d) not a factor
Answer: Option B
18. The relationship between the collector current and a light-generated base current
is
(a) Ic= βdcIλ
(b) Ic= αdcIλ
(c) Ic= λIλ
(d) Ic= β2dcIλ
Answer: Option A
19. An optocoupler usually consists of
(a) two LEDs
(b) an LED and a photodiode
(c) an LED and a phototransistor
(d) both (b) and (c)
Answer: Option D
20. In a transistor amplifier, if the base-emitter junction is open, the collector voltage
is
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(a) Vcc
(b) 0V
(c) floating
(d) 0.2V
Answer: Option A
21. A DMM measuring on open transistor junction shows
(a) 0V
(b) 0.7V
(c) OL
(d) Vcc
Answer: Option C
Chapter 5: Transistor Bias Circuits
1. The maximum value of collector current in a biased transistor is
(a) βdcIB
(b) IC(sat)
(c) greater than IE
(d) IE – IB
Answer: Option B
2. Ideally, a dc load line is a straight line drawn on the collector characteristic curves
between
(a) the Q-point and cutoff
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(b) the Q-point and saturation
(c) VCE(cutoff) and IC(sat)
(d) IB = 0 and IB = IC / βdc
Answer: Option C
3. If a sinusoidal voltage is applied to the base of a biased npn transistor and the
resulting sinusoidal collector voltage is clipped near zero volts, the transistor is
(a) being driven into saturation
(b) being driven into cutoff
(c) operating nonlinearly
(d) answers (a) and (c)
(e) answers (b) and (c)
Answer: Option D
4. The input resistance at the base of a biased transistor depends mainly on
(a) βdc
(b) RB
(c) RE
(d) βdc and RE
Answer: Option D
5. In a voltage-divider biased transistor circuit such as in Figure 5–13, RIN(BASE)
can generally be neglected in calculations when
(a) RIN(BASE) > R2
(b) R2 > 10RIN(BASE)
(c) RIN(BASE) > 10R2
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(d) R1 << R2
Answer: Option C
6. In a certain voltage-divider biased npn transistor, VB is 2.95 V. The dc emitter
voltage is approximately
(a) 2.25 V
(b) 2.95 V
(c) 3.65 V
(d) 0.7 V
Answer: Option A
7. Voltage-divider bias
(a) cannot be independent of βdc
(b) can be essentially independent of βdc
(c) is not widely used
(d) requires fewer components than all the other methods
Answer: Option B
8. Emitter bias is
(a) essentially independent of βdc
(b) very dependent on
(c) provides a stable bias point
(d) answers (a) and (c)
Answer: Option D
9. In an emitter bias circuit, the emitter current
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(a) is 5.3 mA
(b) is 2.7 mA
(c) is 180 mA
(d) cannot be determined
Answer: Option A
10. The disadvantage of base bias is that
(a) it is very complex
(b) it produces low gain
(c) it is too beta dependent
(d) it produces high leakage current
Answer: Option C
11. Collector-feedback bias is
(a) based on the principle of positive feedback
(b) based on beta multiplication
(c) based on the principle of negative feedback
(d) not very stable
Answer: Option C
12. In a voltage-divider biased npn transistor, if the upper voltage-divider resistor (the
one connected to VCC) opens,
(a) the transistor goes into cutoff
(b) the transistor goes into saturation
(c) the transistor burns out
(d) the supply voltage is too high
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Answer: Option A
13. In a voltage-divider biased npn transistor, if the lower voltage-divider resistor (the
one connected to ground) opens,
(a) the transistor is not affected
(b) the transistor may be driven into cutoff
(c) the transistor may be driven into saturation
(d) the collector current will decrease
Answer: Option C
14. In a voltage-divider biased pnp transistor, there is no base current, but the base
voltage is approximately correct. The most likely problem(s) is
(a) a bias resistor is open
(b) the collector resistor is open
(c) the base-emitter junction is open
(d) the emitter resistor is open
(e) answers (a) and (c)
(f) answers (c) and (d)
Answer: Option F
15. If R1 in Figure 5–25 is open, the base voltage is
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(a) +10 V
(b) 0 V
(c) 3.13 V
(d) 0.7 V
Answer: Option B
16. If R1 is open, the collector current in Figure 5–26 is
(a) 5.17 mA
(b) 10 mA
(c) 4.83 mA
(d) 0 mA
Answer: Option D
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Chapter 8: Field-Effect Transistors (FETs)
1. The JFET is
(a) a unipolar device
(b) a voltage-controlled device
(c) a current-controlled device
(d) answers (a) and (c)
(e) answers (a) and (b)
Answer: Option E
2. The channel of a JFET is between the
(a) gate and drain
(b) drain and source
(c) gate and source
(d) input and output
Answer: Option B
3. A JFET always operates with
(a) the gate-to-source pn junction reverse-biased
(b) the gate-to-source pn junction forward-biased
(c) the drain connected to ground
(d) the gate connected to the source
Answer: Option A
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4. For VGS = 0 V, the drain current becomes constant when VDS exceeds
(a) cutoff
(b) VDD
(c) VP
(d) 0 V
Answer: Option C
5. The constant-current region of a FET lies between
(a) cutoff and saturation
(b) cutoff and pinch-off
(c) 0 and IDSS
(d) pinch-off and breakdown
Answer: Option D
6. IDSS is
(a) the drain current with the source shorted
(b) the drain current at cutoff
(c) the maximum possible drain current
(d) the midpoint drain current
Answer: Option C
7. Drain current in the constant-current region increases when
(a) the gate-to-source bias voltage decreases
(b) the gate-to-source bias voltage increases
(c) the drain-to-source voltage increases
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(d) the drain-to-source voltage decreases
Answer: Option A
8. In a certain FET circuit, VGS = 0 V, VDD = 15 V, IDSS = 15 mA, and RD = 470Ω.
If RD is decreased to 330Ω, IDSS is
(a) 19.5 mA
(b) 10.5 mA
(c) 15 mA
(d) 1 mA
Answer: Option C
9. At cutoff, the JFET channel is
(a) at its widest point
(b) completely closed by the depletion region
(c) extremely narrow
(d) reverse-biased
Answer: Option B
10. A certain JFET datasheet gives The pinch-off voltage, VP,
(a) cannot be determined
(b) is –4V
(c) depends on VGS
(d) is +4V
Answer: Option B
11. The JFET in Question 10
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(a) is an n channel
(b) is a p channel
(c) can be either
Answer: Option A
12. For a certain JFET, IGSS = 10 nA at VGS =10 V. The input resistance is
(a) 100 MΩ
(b) 1 MΩ
(c) 1000 MΩ
(d) 1000 mΩ
Answer: Option C
13. For a certain p-channel JFET, VGS(off ) = 8 V. The value of VGS for an
approximate midpoint bias is
(a) 4 V
(b) 0 V
(c) 1.25 V
(d) 2.34 V
Answer: Option D
14. In a self-biased JFET, the gate is at
(a) a positive voltage
(b) 0 V
(c) a negative voltage
(d) ground
Answer: Option B
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15. The drain-to-source resistance in the ohmic region depends on
(a) VGS
(b) the Q-point values
(c) the slope of the curve at the Q-point
(d) all of these
Answer: Option D
16. To be used as a variable resistor, a JFET must be
(a) an n-channel device
(b) a p-channel device
(c) biased in the ohmic region
(d) biased in saturation
Answer: Option C
17. When a JFET is biased at the origin, the ac channel resistance is determined by
(a) the Q-point values
(b) VGS
(c) the transconductance
(d) answers (b) and (c)
Answer: Option D
18. A MOSFET differs from a JFET mainly because
(a) of the power rating
(b) the MOSFET has two gates
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(c) the JFET has a pn junction
(d) MOSFETs do not have a physical channel
Answer: Option C
19. A D-MOSFET operates in
(a) the depletion mode only
(b) the enhancement mode only
(c) the ohmic region only
(d) both the depletion and enhancement modes
Answer: Option D
20. An n-channel D-MOSFET with a positive VGS is operating in
(a) the depletion mode
(b) the enhancement mode
(c) cutoff
(d) saturation
Answer: Option B
21. A certain p-channel E-MOSFET has a If VGS = 0 V, the drain current is
(a) 0 A
(b) ID(on)
(c) maximum
(d) IDSS
Answer: Option A
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22. In an E-MOSFET, there is no drain current until VGS
(a) reaches VGS(th)
(b) is positive
(c) is negative
(d) equals 0 V
Answer: Option A
23. All MOS devices are subject to damage from
(a) excessive heat
(b) electrostatic discharge
(c) excessive voltage
(d) all of these
Answer: Option D
24. A certain D-MOSFET is biased at VGS = 0 V. Its datasheet specifies IDSS= 20
mA and the value of the drain current
(a) is 0 A
(b) cannot be determined
(c) is 20 mA
Answer: Option C
25. An IGBT is generally used in
(a) low-power applications
(b) rf applications
(c) high-voltage applications
(d) low-current applications
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Answer: Option C
-End-
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