Multiple Choice Questions and Answers on FET
Multiple Choice Questions and Answers on FET ( Field Effect Transistors )
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- Question Bank in Electronics & Communication Engineering by Prem R Chadha
- A Handbook on Electronics Engineering – Illustrated Formulae & Key Theory Concepts
Q1. A JFET has three terminals, namely …………
- cathode, anode, grid
- emitter, base, collector
- source, gate, drain
- none of the above
Answer : 3
Q2. A JFET is similar in operation to …………. valve
- diode
- pentode
- triode
- tetrode
Answer : 2
Q3. A JFET is also called …………… transistor
- unipolar
- bipolar
- unijunction
- none of the above
Answer : 1
Q4. A JFET is a ………… driven device
- current
- voltage
- both current and voltage
- none of the above
Answer : 2
Q5. The gate of a JFET is ………… biased
- reverse
- forward
- reverse as well as forward
- none of the above
Answer : 1
Q6. The input impedance of a JFET is …………. that of an ordinary transistor
- equal to
- less than
- more than
- none of the above
Answer : 3
Q7. In a p-channel JFET, the charge carriers are …………..
- electrons
- holes
- both electrons and holes
- none of the above
Answer : 2
Q8. When drain voltage equals the pinch-off-voltage, then drain current …………. with the increase in drain voltage
- decreases
- increases
- remains constant
- 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 …………..
- is decreased
- is increased
- remains the same
- none of the above
Answer : 1
Q10. A MOSFET has …………… terminals
- two
- five
- four
- three
Answer : 4
Q11. A MOSFET can be operated with ……………..
- negative gate voltage only
- positive gate voltage only
- positive as well as negative gate voltage
- none of the above
Answer : 3
Q12. A JFET has ……….. power gain
- small
- very high
- very small
- none of the above
Answer : 2
Q13. The input control parameter of a JFET is ……………
- gate voltage
- source voltage
- drain voltage
- gate current
Answer : 1
Q14. A common base configuration of a pnp transistor is analogous to ………… of a JFET
- common source configuration
- common drain configuration
- common gate configuration
- none of the above
Answer : 3
Q15. A JFET has high input impedance because …………
- it is made of semiconductor material
- input is reverse biased
- of impurity atoms
- none of the above
Answer : 2
Q16. In a JFET, when drain voltage is equal to pinch-off voltage, the depletion layers ………
- almost touch each other
- have large gap
- have moderate gap
- none of the above
Answer : 1
Q17. In a JFET, IDSS is known as …………..
- drain to source current
- drain to source current with gate shorted
- drain to source current with gate open
- none of the above
Answer : 2
Q18. The two important advantages of a JFET are …………..
- high input impedance and square-law property
- inexpensive and high output impedance
- low input impedance and high output impedance
- none of the above
Answer : 1
Q19. …………. has the lowest noise-level
- triode
- ordinary trnsistor
- tetrode
- JFET
Answer : 4
Q20. A MOSFET is sometimes called ………. JFET
- many gate
- open gate
- insulated gate
- shorted gate
Answer : 3
Q21. Which of the following devices has the highest input impedance?
- JFET
- MOSFET
- Crystal diode
- ordinary transistor
Answer : 2
Q22. A MOSFET uses the electric field of a ………. to control the channel current
- capacitor
- battery
- generator
- none of the above
Answer : 1
Q23. The pinch-off voltage in a JFET is analogous to ………. voltage in a vacuum tube
- anode
- cathode
- grid cut off
- 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
- forward
- reverse
- not
- none of the above
Answer : 2
Q26. If the gate of a JFET is made less negative, the width of the conducting channel……….
- remains the same
- is decreased
- is increased
- none of the above
Answer : 3
Q27. The pinch-off voltage of a JFET is about ……….
- 5 V
- 0.6 V
- 15 V
- 25 V
Answer : 1
Q28. The input impedance of a MOSFET is of the order of ………..
- Ω
- a few hundred Ω
- kΩ
- several MΩ
Answer : 4
Q29. The gate voltage in a JFET at which drain current becomes zero is called ……….. voltage
- saturation
- pinch-off
- active
- cut-off
Answer : 2
Q30. This question will be available soon
Q31. In a FET, there are ……….. pn junctions at the sides
- three
- four
- five
- two
Answer : 4
Q32. The transconductance of a JFET ranges from ……………..
- 100 to 500 mA/V
- 500 to 1000 mA/V
- 0.5 to 30 mA/V
- above 1000 mA/V
Answer : 3
Q33. The source terminal of a JEFT corresponds to ………….. of a vacuum tube
- plate
- cathode
- grid
- none of the above
Answer : 2
Q34. The output characteristics of a JFET closely resemble the output characteristics of a ………. valve
- pentode
- tetrode
- triode
- diode
Answer : 1
Q35. If the cross-sectional area of the channel in n-channel JEFT increases, the drain current ……….
- is increased
- is decreased
- remains the same
- none of the above
Answer : 1
Q36. The channel of a JFET is between the …………….
- gate and drain
- drain and source
- gate and source
- input and output
Answer : 2
Q37. For VGS = 0 V, the drain current becomes constant when VDS exceeds ………
- cut off
- VDD
- VP
- o V
Answer : 3
Q38. A certain JFET data sheet gives VGS(off) = -4 V. The pinch-off voltage Vp is ……..
- +4 V
- -4 V
- dependent on VGS
- data insufficient
Answer : 1
Q39. The constant-current region of a JFET lies between
- cut off and saturation
- cut off and pinch-off
- o and IDSS
- pinch-off and breakdown
Answer : 4
Q40. At cut-off, the JFET channel is ……….
- at its widest point
- completely closed by the depletion region
- extremely narrow
- reverse baised
Answer : 2
Q41. A MOSFET differs from a JFET mainly because ………………
- of power rating
- the MOSFET has two gates
- the JFET has a pn junction
- 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 …………
- 20 mA
- 0 mA
- 40 mA
- 10 mA
Answer : 1
Q43. A n-channel D-MOSFET with a positive VGS is operating in …………
- the depletion-mode
- the enhancement-mode
- cut off
- saturation
Answer : 2
Q44. A certain p-channel E-MOSFET has VGS(th) = -2V. If VGS= 0V, the drain current is ……….
- 0 mA
- ID(on)
- maximum
- IDSS
Answer : 1
Q45. In a common-source JFET amplifier, the output voltage is …………………
- 180o out of phase with the input
- in phase with the input
- 90o out of phase with the input
- 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
- 11.4
- 8.75
- 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 …………
- 450
- 45
- 2.52
- 4.5
Answer : 4
Q48. A certain common-source JFET has a voltage gain of 10. If the source bypass capacitor is removed, ……………….
- the voltage gain will increase
- the transconductance will increase
- the voltage gain will decrease
- 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 ………..
- 2.05 V
- 25 V
- 0.5 V
- 1.89 V
Answer : 4
Q50. If load resistance in the above question (Q.49) is removed, the output voltage will …………
- increase
- decrease
- stay the same
- be zero
Answer : 1
Q.51. When not in use, MOSFET pins are kept at the same potential through the use of …………
- shipping foil
- nonconductive foam
- conductive foam
- 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 …………..
- low output impedance
- capacitive reactance
- high input impedance
- inductive reactance
Answer: 3
Q.53. A “U” shaped, opposite-polarity material built near a JFET-channel center is called the ……….
- gate
- block
- drain
- 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?
- short D to S
- open G to D
- open D to SS
- nothing
Answer: 4
Q.55. In the constant-current region, how will the IDS change in an n-channel JFET?
- As VGS decreases ID decreases.
- As VGS increases ID increases
- As VGS decreases ID remains constant.
- As VGS increases ID remains constant.
Answer: 1
Q.56. IDSS can be defined as ………
- the minimum possible drain current
- the maximum possible current with VGS held at –4 V
- the maximum possible current with VGS held at 0 V
- the maximum drain current with the source shorted
Answer: 3
Q.57. The input impedance of a common-gate configured JFET is …………
- very low
- low
- high
- very high
Answer: 1
Q.58. A very simple bias for a D-MOSFET is called ……..
- self biasing
- gate biasing
- zero biasing
- voltage-divider biasing
Answer: 3
Q.59. With the E-MOSFET, when gate input voltage is zero, drain current is …..
- at saturation
- zero
- IDSS
- 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?
- 6 V
- 10 V
- 24 V
- 30 V
Answer: 1
Q.61. When an input signal reduces the channel size, the process is called …….
- enhancement
- substrate connecting
- gate charge
- depletion
Answer: 4
Q.62. Which JFET configuration would connect a high-resistance signal source to a low-resistance load ?
- source follower
- common-source
- common-drain
- common-gate
Answer: 1
Q.63. When VGS = 0 V, a JFET is……….
- saturated
- an analog device
- an open switch
- an open switch
Answer: 1
Q.64. The electrons flow through a p-channel JFET from ……….. to …………..
- from source to drain
- from source to gate
- from drain to gate
- from drain to source
Answer: 4
Q.65. When applied input voltage varies the resistance of a channel, the result is called…………..
- saturization
- polarization
- cutoff
- field effect
Answer: 4
Q.66. When is a vertical channel E-MOSFET used?
- for high frequencies
- for high voltages
- for high currents
- for high resistances
Answer: 3
Q.67. When the JFET is no longer able to control the current, this point is called the …………
- breakdown region
- depletion region
- saturation point
- pinch-off region
Answer: 1
Q.68. With a JFET, a ratio of output current change against an input voltage change is called as ………..
- transconductance
- siemens
- resistivity
- gain
Answer: 1
Q.69. Which type of JFET bias requires a negative supply voltage?
- feedback
- source
- gate
- voltage divider
Answer: 3
Q.70. How will a D-MOSFET input impedance change with signal frequency?
- As frequency increases input impedance increases.
- As frequency increases input impedance is constant.’
- As frequency decreases input impedance increases.
- As frequency decreases input impedance is constant.
Answer: 3
Q.71. The type of bias most often used with E-MOSFET circuits is………….
- constant current
- drain-feedback
- voltage-divider
- zero biasing
Answer: 2
Q.72. The transconductance curve of a JFET is a graph of …………… vs ……….
- IS versus VDS
- IC versus VCE
- ID versus VGS
- ID × RDS
Answer: 3
Q.73. The common-source JFET amplifier has ………..
- a very high input impedance and a relatively low voltage gain
- a high input impedance and a very high voltage gain
- a high input impedance and a voltage gain less than 1
- 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 ………..
- in parallel
- with separate insulation
- with separate inputs
- in series
Answer: 4
Q.75. Which component is considered to be an “OFF” devic.
- transistor
- JFET
- D-MOSFET
- E-MOSFET
Answer: 4
Q.76. In an n-channel JFET, what will happen at the pinch-off voltage?
- the value of VDS at which further increases in VDS will cause no further increase in ID
- the value of VGS at which further decreases in VGS will cause no further increases in ID
- the value of VDG at which further decreases in VDG will cause no further increases in ID
- the value of VDS at which further increases in VGS will cause no further increases in ID
Answer: 1
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