Multiple Choice Questions and Answers on FET

Multiple Choice Questions and Answers By January 9, 2020
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Multiple Choice Questions and Answers on FET ( Field Effect Transistors )

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Q1. A JFET has three terminals, namely …………

  1. cathode, anode, grid
  2. emitter, base, collector
  3. source, gate, drain
  4. none of the above

Answer : 3

Q2. A JFET is similar in operation to …………. valve

  1. diode
  2. pentode
  3. triode
  4. tetrode

Answer : 2

Q3. A JFET is also called …………… transistor

  1. unipolar
  2. bipolar
  3. unijunction
  4. none of the above

Answer : 1

Q4. A JFET is a ………… driven device

  1. current
  2. voltage
  3. both current and voltage
  4. none of the above

Answer : 2

Q5. The gate of a JFET is ………… biased

  1. reverse
  2. forward
  3. reverse as well as forward
  4. none of the above

Answer : 1

Q6. The input impedance of a JFET is …………. that of an ordinary transistor

  1. equal to
  2. less than
  3. more than
  4. none of the above

Answer : 3

Q7. In a p-channel JFET, the charge carriers are …………..

  1. electrons
  2. holes
  3. both electrons and holes
  4. none of the above

Answer : 2

Q8. When drain voltage equals the pinch-off-voltage, then drain current …………. with the increase in drain voltage

  1. decreases
  2. increases
  3. remains constant
  4. none of the above

Answer : 3

Q9. If the reverse bias on the gate of a JFET is increased, then width of the conducting channel …………..

  1. is decreased
  2. is increased
  3. remains the same
  4. none of the above

Answer : 1

Q10. A MOSFET has …………… terminals

  1. two
  2. five
  3. four
  4. three

Answer : 4

Q11. A MOSFET can be operated with ……………..

  1. negative gate voltage only
  2. positive gate voltage only
  3. positive as well as negative gate voltage
  4. none of the above

Answer : 3

Q12. A JFET has ……….. power gain

  1. small
  2. very high
  3. very small
  4. none of the above

Answer : 2

Q13. The input control parameter of a JFET is ……………

  1. gate voltage
  2. source voltage
  3. drain voltage
  4. gate current

Answer : 1

Q14. A common base configuration of a pnp transistor is analogous to ………… of a JFET

  1. common source configuration
  2. common drain configuration
  3. common gate configuration
  4. none of the above

Answer : 3

Q15. A JFET has high input impedance because …………

  1. it is made of semiconductor material
  2. input is reverse biased
  3. of impurity atoms
  4. none of the above

Answer : 2

Q16. In a JFET, when drain voltage is equal to pinch-off voltage, the depletion layers ………

  1. almost touch each other
  2. have large gap
  3. have moderate gap
  4. none of the above

Answer : 1

Q17. In a JFET, IDSS is known as …………..

  1. drain to source current
  2. drain to source current with gate shorted
  3. drain to source current with gate open
  4. none of the above

Answer : 2

Q18. The two important advantages of a JFET are …………..

  1. high input impedance and square-law property
  2. inexpensive and high output impedance
  3. low input impedance and high output impedance
  4. none of the above

Answer : 1

Q19. …………. has the lowest noise-level

  1. triode
  2. ordinary trnsistor
  3. tetrode
  4. JFET

Answer : 4

Q20. A MOSFET is sometimes called ………. JFET

  1. many gate
  2. open gate
  3. insulated gate
  4. shorted gate

Answer : 3

Q21. Which of the following devices has the highest input impedance?

  1. JFET
  2. MOSFET
  3. Crystal diode
  4. ordinary transistor

Answer : 2

Q22. A MOSFET uses the electric field of a ………. to control the channel current

  1. capacitor
  2. battery
  3. generator
  4. none of the above

Answer : 1

Q23. The pinch-off voltage in a JFET is analogous to ………. voltage in a vacuum tube

  1. anode
  2. cathode
  3. grid cut off
  4. none of the above

Answer : 3

Q24. This question will be available soon

 

Q25. In class A operation, the input circuit of a JFET is ………. biased

  1. forward
  2. reverse
  3. not
  4. none of the above

Answer : 2

Q26. If the gate of a JFET is made less negative, the width of the conducting channel……….

  1. remains the same
  2. is decreased
  3. is increased
  4. none of the above

Answer : 3

Q27. The pinch-off voltage of a JFET is about ……….

  1. 5 V
  2. 0.6 V
  3. 15 V
  4. 25 V

Answer : 1

Q28. The input impedance of a MOSFET is of the order of ………..

  1. Ω
  2. a few hundred Ω
  3. kΩ
  4. several MΩ

Answer : 4

Q29. The gate voltage in a JFET at which drain current becomes zero is called ……….. voltage

  1. saturation
  2. pinch-off
  3. active
  4. cut-off

Answer : 2

Q30. This question will be available soon

 

Q31. In a FET, there are ……….. pn junctions at the sides

  1. three
  2. four
  3. five
  4. two

Answer : 4

Q32. The transconductance of a JFET ranges from ……………..

  1. 100 to 500 mA/V
  2. 500 to 1000 mA/V
  3. 0.5 to 30 mA/V
  4. above 1000 mA/V

Answer : 3

Q33. The source terminal of a JEFT corresponds to ………….. of a vacuum tube

  1. plate
  2. cathode
  3. grid
  4. none of the above

Answer : 2

Q34. The output characteristics of a JFET closely resemble the output characteristics of a ………. valve

  1. pentode
  2. tetrode
  3. triode
  4. diode

Answer : 1

Q35. If the cross-sectional area of the channel in n-channel JEFT increases, the drain current ……….

  1. is increased
  2. is decreased
  3. remains the same
  4. none of the above

Answer : 1

Q36. The channel of a JFET is between the …………….

  1. gate and drain
  2. drain and source
  3. gate and source
  4. input and output

Answer : 2

Q37. For VGS = 0 V, the drain current becomes constant when VDS exceeds ………

  1. cut off
  2. VDD
  3. VP
  4. o V

Answer : 3

Q38. A certain JFET data sheet gives  VGS(off) = -4 V. The pinch-off voltage Vp is ……..

  1. +4 V
  2. -4 V
  3. dependent on VGS
  4. data insufficient

Answer : 1

Q39. The constant-current region of a JFET lies between

  1. cut off and saturation
  2. cut off and pinch-off
  3. o and IDSS
  4. pinch-off and breakdown

Answer : 4

Q40. At cut-off, the JFET channel is ……….

  1. at its widest point
  2. completely closed by the depletion region
  3. extremely narrow
  4. reverse baised

Answer : 2

Q41. A MOSFET differs from a JFET mainly because ………………

  1. of power rating
  2. the MOSFET has two gates
  3. the JFET has a pn junction
  4. none of the above

Answer : 3

Q42. A certain D-MOSFET is biased at VGS = 0 V. Its data sheet specifies IDSS = 20mA and VGS(off)  = -5 V. The value of the drain current is …………

  1. 20 mA
  2. 0 mA
  3. 40 mA
  4. 10 mA

Answer : 1

Q43. A n-channel D-MOSFET with a positive VGS is operating in …………

  1. the depletion-mode
  2. the enhancement-mode
  3. cut off
  4. saturation

Answer : 2

Q44. A certain p-channel E-MOSFET has VGS(th)  = -2V. If VGS= 0V, the drain current is ……….

  1. 0 mA
  2. ID(on)
  3. maximum
  4. IDSS

Answer : 1

Q45. In a common-source JFET amplifier, the output voltage is …………………

  1. 180o out of phase with the input
  2. in phase with the input
  3. 90o out of phase with the input
  4. taken at the source

Answer : 1

Q46. In a certain common-source D-MOSFET amplifier, Vds =3.2 V r.m. and Vgs = 280 mV r.m.s. The voltage gain is …………

  1. 1
  2. 11.4
  3. 8.75
  4. 3.2

Answer : 2

Q47. In a certain CS JFET amplifier,  RD= 1kΩ , RS= 560 Ω , VDD=10V and gm= 4500 μS. If the source resistor is completely bypassed, the voltage gain is …………

  1. 450
  2. 45
  3. 2.52
  4. 4.5

Answer : 4

Q48. A certain common-source JFET has a voltage gain of 10. If the source bypass capacitor is removed, ……………….

  1. the voltage gain will increase
  2. the transconductance will increase
  3. the voltage gain will decrease
  4. the Q-point will shift

Answer : 3

Q49. A CS JFET amplifier has a load resistance of 10 kΩ ,  RD= 820Ω . If gm= 5mS and Vin= 500 mV, the output signal voltage is ………..

  1. 2.05 V
  2. 25 V
  3. 0.5 V
  4. 1.89 V

Answer : 4

Q50. If load resistance in the above question (Q.49) is removed, the output voltage will …………

  1. increase
  2. decrease
  3. stay the same
  4. be zero

Answer : 1

Q.51. When not in use, MOSFET pins are kept at the same potential through the use of …………

  1. shipping foil
  2. nonconductive foam
  3. conductive foam
  4. a wrist strap

Answer: 3

Q.52. D-MOSFETs are sometimes used in series to construct a cascode high-frequency amplifier to overcome the loss of …………..

  1. low output impedance
  2. capacitive reactance
  3. high input impedance
  4. inductive reactance

Answer: 3

Q.53. A “U” shaped, opposite-polarity material built near a JFET-channel center is called the ……….

  1. gate
  2. block
  3. drain
  4. heat sink

Answer: 1

Q.54. When testing an n-channel D-MOSFET, resistance G to D = , resistance G to S = , resistance D to SS =  and 500 , depending on the polarity of the ohmmeter, and resistance D to S = 500 . What is wrong?

  1. short D to S
  2. open G to D
  3. open D to SS
  4. nothing

Answer: 4

Q.55. In the constant-current region, how will the IDS change in an n-channel JFET?

  1. As VGS decreases ID decreases.
  2. As VGS increases ID increases
  3. As VGS decreases ID remains constant.
  4. As VGS increases ID remains constant.

Answer: 1

Q.56. IDSS can be defined as ………

  1. the minimum possible drain current
  2. the maximum possible current with VGS held at –4 V
  3. the maximum possible current with VGS held at 0 V
  4. the maximum drain current with the source shorted

Answer: 3

Q.57. The input impedance of a common-gate configured JFET is …………

  1. very low
  2. low
  3. high
  4. very high

Answer: 1

Q.58. A very simple bias for a D-MOSFET is called ……..

  1. self biasing
  2. gate biasing
  3. zero biasing
  4. voltage-divider biasing

Answer: 3

Q.59. With the E-MOSFET, when gate input voltage is zero, drain current is …..

  1. at saturation
  2. zero
  3. IDSS
  4. widening the channel

Answer: 2

Q.60. With a 30-volt VDD, and an 8-kilohm drain resistor, what is the E-MOSFET Q point voltage, with ID = 3 mA?

  1. 6 V
  2. 10 V
  3. 24 V
  4. 30 V

Answer: 1

Q.61. When an input signal reduces the channel size, the process is called …….

  1. enhancement
  2. substrate connecting
  3. gate charge
  4. depletion

Answer: 4

Q.62. Which JFET configuration would connect a high-resistance signal source to a low-resistance load ?

  1. source follower
  2. common-source
  3. common-drain
  4. common-gate

Answer: 1

Q.63. When VGS = 0 V, a JFET is……….

  1. saturated
  2. an analog device
  3. an open switch
  4. an open switch

Answer: 1

Q.64. The electrons flow through a p-channel JFET from ……….. to …………..

  1. from source to drain
  2. from source to gate
  3. from drain to gate
  4. from drain to source

Answer: 4

Q.65. When applied input voltage varies the resistance of a channel, the result is called…………..

  1. saturization
  2. polarization
  3. cutoff
  4. field effect

Answer: 4

Q.66. When is a vertical channel E-MOSFET used?

  1. for high frequencies
  2. for high voltages
  3. for high currents
  4. for high resistances

Answer: 3

Q.67. When the JFET is no longer able to control the current, this point is called the …………

  1. breakdown region
  2. depletion region
  3. saturation point
  4. pinch-off region

Answer: 1

Q.68.  With a JFET, a ratio of output current change against an input voltage change is called as ………..

  1. transconductance
  2. siemens
  3. resistivity
  4. gain

Answer: 1

Q.69. Which type of JFET bias requires a negative supply voltage?

  1. feedback
  2. source
  3. gate
  4. voltage divider

Answer: 3

Q.70. How will a D-MOSFET input impedance change with signal frequency?

  1. As frequency increases input impedance increases.
  2. As frequency increases input impedance is constant.’
  3. As frequency decreases input impedance increases.
  4. As frequency decreases input impedance is constant.

Answer: 3

Q.71. The type of bias most often used with E-MOSFET circuits is………….

  1. constant current
  2. drain-feedback
  3. voltage-divider
  4. zero biasing

Answer: 2

Q.72. The transconductance curve of a JFET is a graph of …………… vs ……….

  1. IS versus VDS
  2. IC versus VCE
  3. ID versus VGS
  4. ID × RDS

Answer: 3

Q.73. The common-source JFET amplifier has ………..

  1. a very high input impedance and a relatively low voltage gain
  2. a high input impedance and a very high voltage gain
  3. a high input impedance and a voltage gain less than 1
  4. no voltage gain

Answer: 1

Q.74. The overall input capacitance of a dual-gate D-MOSFET is lower because the devices are usually connected ………..

  1. in parallel
  2. with separate insulation
  3. with separate inputs
  4. in series

Answer: 4

Q.75. Which component is considered to be an “OFF” devic.

  1. transistor
  2. JFET
  3. D-MOSFET
  4. E-MOSFET

Answer: 4

Q.76.  In an n-channel JFET, what will happen at the pinch-off voltage?

  1. the value of VDS at which further increases in VDS will cause no further increase in ID
  2. the value of VGS at which further decreases in VGS will cause no further increases in ID
  3. the value of VDG at which further decreases in VDG will cause no further increases in ID
  4. the value of VDS at which further increases in VGS will cause no further increases in ID

Answer: 1

 

 

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