# Field Effect Transistor (FET) MCQ

## 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

Q.3. For low values of VDS, the JFET behaves like a

• resistance
• constant voltage device
• constant current device
• negative resistor

Q.4. When VDS reaches the pinch off voltage VP, the drain current becomes

• low
• zero
• constant (saturated)
• reversed

Q.5. In an n-channel JFET, the drain current reaches its maximum value when VGS is

• negative
• zero
• positive
• equal to VP

Q.6. In an n-channel JFET

• the current carriers are holes
• the current carriers are electrons
• VGS 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
• VGS is negative
• the input resistance is very small

Answer: the current carriers are holes

Q.8. For an n-channel JFET

• VGS can vary between zero negatively to VGSO
• VGS can vary between zero positively to VGSO
• pinch off occurs for positive VGS
• VDD is negative

Answer: VGS can vary between zero negatively to VGSO

Q.9. A FET cannot operate at VGS = 0 V. The FET is

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

Q.10. The transconductance gm 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}}

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 )

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
• Vds
• external drain resistance
• transconductance and gate to source voltage

Q.16. A CS amplifier has a drain load RD = 1 kΩ and an external load resistance of RL = 1 kΩ. If gm = 10 mS, the voltage gain will be

• 10
• 5
• 20
• 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

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

• 0.82
• 1
• 1.22
• 9

Q.19. In a common gate amplifier, the transconductance is gm = 6000 µS, RG = 1 MΩ. The total input resistance will be

• 1666 Ω
• 166.6 Ω
• 1 MΩ
• 100166.6 Ω

Q.20. In a CD amplifier, IDSS = 5 mA at VGS = 10 V. If the resistor RG is 20 MΩ. The total input of the resistance will be

• 20 MΩ
• 200 MΩ
• 40 MΩ
• 100 MΩ