## Field Effect Transistor (FET) MCQ

Field Effect Transistor (FET) MCQ, Multiple Choice Questions Field Effect Transistor (FET), Junction Field Transistor (JFET) MCQ, MOSFET MCQ, Engineering MCQ,

## Objective Type Questions

Q.1. The JFET is

- a bipolar device
- unipolar device
- current controlled device
- voltage controlled device

**Answer: **a bipolar & unipolar device

Q.2. The channel of a JFET exists between

- gate and source
- drain and source
- gate and drain
- input and output

**Answer: **drain and source

Q.3. For low values of V_{DS}, the JFET behaves like a

- resistance
- constant voltage device
- constant current device
- negative resistor

**Answer:** resistance

Q.4. When V_{DS} reaches the pinch off voltage V_{P}, the drain current becomes

- low
- zero
- constant (saturated)
- reversed

**Answer:** constant (saturated)

Q.5. In an n-channel JFET, the drain current reaches its maximum value when V_{GS} is

- negative
- zero
- positive
- equal to V
_{P}

**Answer:** equal to V_{P}

Q.6. In an n-channel JFET

- the current carriers are holes
- the current carriers are electrons
- V
_{GS}is positive - the input resistance is very low

**Answer:** the current carriers are electrons

Q.7. In a p-channel JFET

- the current carriers are electrons
- the current carriers are holes
- V
_{GS}is negative - the input resistance is very small

**Answer:** the current carriers are holes

Q.8. For an n-channel JFET

- V
_{GS}can vary between zero negatively to V_{GSO} - V
_{GS}can vary between zero positively to V_{GSO} - pinch off occurs for positive V
_{GS} - V
_{DD}is negative

**Answer:** V_{GS} can vary between zero negatively to V_{GSO}

Q.9. A FET cannot operate at V_{GS} = 0 V. The FET is

- JFET
- D-MOSFET
- E-MOSFET
- both JFET and D-MOSFET

**Answer:** E-MOSFET

Q.10. The transconductance *g _{m}* of JFET is defined as

- \frac{\Delta I_{D}}{\Delta V_{GS}}
- \frac{\Delta I_{D}}{\Delta V_{DS}}
- \frac{\Delta V_{GS}}{\Delta I_{D}}
- \frac{\Delta I_{DSS}}{\Delta I_{D}}

**Answer: **\frac{\Delta I_{D}}{\Delta V_{GS}}

Q.11. The amplification factor µ of JFET is given by

- g_{m}\times r_{d}
- \frac{g_{m}} {r_{d}}
- g_{m}\cdot I_{DSS}
- g_{m}\left ( 1-\frac{V_{GS}}{V_{P}} \right )

**Answer: **g_{m}\times r_{d}

Q.12. A channel is induced in an E-MOSFET by the application of a

- V_{GS}< \left ( V_{GS} \right )th
- V_{GS}> V_{P}
- V_{GS}> \left ( V_{GS} \right )th
- V_{DS}> V_{P}

**Answer:** V_{GS}> \left ( V_{GS} \right )th

Q.13. The Shockley equation is given by

- I_{D}=I_{DSS}\left [ 1-\frac{V_{GS}}{V_{P}} \right ]^{2}
- I_{D}=I_{DSS}\left [ 1-\frac{V_{GS}}{V_{P}} \right ]
- g_{m}=g_{mo}\left [ 1-\frac{V_{GS}}{V_{P}} \right ]
- I_{D}=C\left [ V_{GS}-V_{GS}(th) \right ]^{2}

**Answer:** I_{D}=I_{DSS}\left [ 1-\frac{V_{GS}}{V_{P}} \right ]^{2}

Q.14. Ideally, the equivalent circuit of a FET consists of

- a resistance between drain and source
- a current source between the gate and the source
- a current source between the drain and the source
- a current source between the gate and the drain

**Answer:** a current source between the drain and the source

Q.15. The magnitude of the current source in the AC equivalent circuit of a FET depends on

- the de supply voltage
- V
_{ds} - external drain resistance
- transconductance and gate to source voltage

**Answer:** external drain resistance

Q.16. A CS amplifier has a drain load R_{D} = 1 kΩ and an external load resistance of R_{L} = 1 kΩ. If *g _{m}* = 10 mS, the voltage gain will be

- 10
- 5
- 20
- 1

**Answer:** 1

Q.17. If the external load resistance is removed in Q.16, the voltage gain will be

- decrease
- increase
- remain the same
- become zero

**Answer:** increase

Q.18. In a CD amplifier, R_{S} = 500 Ω, and the transconductance is 9000 µS. The voltage gain will be

- 0.82
- 1
- 1.22
- 9

**Answer:** 0.82

Q.19. In a common gate amplifier, the transconductance is *g _{m}* = 6000 µS, R

_{G}= 1 MΩ. The total input resistance will be

- 1666 Ω
- 166.6 Ω
- 1 MΩ
- 100166.6 Ω

**Answer:** 166.6 Ω

Q.20. In a CD amplifier, I_{DSS} = 5 mA at V_{GS} = 10 V. If the resistor R_{G} is 20 MΩ. The total input of the resistance will be

- 20 MΩ
- 200 MΩ
- 40 MΩ
- 100 MΩ

**Answer:** 20 MΩ

Q.21. If there is an internal open between the source and the drain in a CS amplifier, the drain voltage will be

- 0 V
- V
_{GS} - V
_{DD} - V
_{DD}/2

**Answer:** V_{DD}