**Multiple Choice Questions and Answers on FET ( Field Effect Transistors )**

**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, I _{DSS} 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 V _{GS} = 0 V, the drain current becomes constant when V_{DS} exceeds ………**

- cut off
- V
_{DD} - V
_{P} - o V

**Answer : 3**

**Q38. A certain JFET data sheet gives V _{GS(off)} = -4 V. The pinch-off voltage V_{p} is ……..**

- +4 V
- -4 V
- dependent on V
_{GS} - 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 I
_{DSS} - 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 V _{GS} = 0 V. Its data sheet specifies I_{DSS }= 20mA and V_{GS(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 V _{GS} is operating in …………**

- the depletion-mode
- the enhancement-mode
- cut off
- saturation

**Answer : 2**

**Q44. A certain p-channel E-MOSFET has V _{GS(th)} = -2V. If V_{GS}= 0V, the drain current is ……….**

- 0 mA
- I
_{D(on)} - maximum
- I
_{DSS}

**Answer : 1**

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

- 180
^{o}out of phase with the input - in phase with the input
- 90
^{o}out of phase with the input - taken at the source

**Answer : 1**

**Q46. In a certain common-source D-MOSFET amplifier, V _{ds} =3.2 V r.m. and V_{gs} = 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, R _{D}= 1kΩ , R_{S}= 560 Ω , V_{DD}=10V and g_{m}= 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 , R _{D}= 820Ω . If g_{m}= 5mS and V_{in}= 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**