# Field-Effect Transistors (FET) MCQ (Part-2)

## Field-Effect Transistors (FET) MCQ

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Field-Effect Transistors (FET) MCQ (Part-1)

### Multiple-Choice Questions

Q.1. 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

Q.2. The pinch-off voltage of a JFET is about …….

• 5 V
• 0.6 V
• 15 V
• 25 V

Q.3. The input impedance of a MOSFET is of the order of …………..

• Ω
• a few hundred Ω
• k Ω
• several M Ω

Q.4. The gate voltage in a JFET at which drain current becomes zero is called ………….. voltage.

• saturation
• pinch-off
• active
• cut-off

Q.5. The drain current ID in a JFET 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 )^{2}
• I_{D}=I_{DSS}\left ( 1-\frac{V_{P}}{V_{GS}} \right )^{2}
• I_{D}=I_{DSS}\left ( 1+\frac{V_{P}}{V_{GS}} \right )^{2}

Answer: I_{D}=I_{DSS}\left ( 1-\frac{V_{GS}}{V_{P}} \right )^{2}

Q.6. In a FET, there are …………… pn junctions at the sides.

• three
• four
• five
• two

Q.7. 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

Q.8. The source terminal of a JFET corresponds to …………… of a vacuum tube.

• plate
• cathode
• grid
• none of the above

Q.9. The output characteristics of a JFET closely resemble the output characteristics of a …………… valve.

• pentode
• tetrode
• triode
• diode

Q.10. If the cross-sectional area of the channel in n-channel JFET increases, the drain current ……………

• is increased
• is decreased
• remains the same
• none of the above

Q.11. The channel of a JFET is between the ……………

• gate and drain
• drain and source
• gate and source
• input and output

Q.12. For VGS= 0 V, the drain current becomes constant when VDS exceeds ……………

• cut off
• VDD
• VP
• 0 V

Q.13. A certain JFET datasheet gives VGS(off) = − 4 V. The pinch-off voltage VP is ………….

• + 4 V
• − 4 V
• dependent on VGS
• data insufficient

Q.14. The constant-current region of a JFET lies between ……………

• cut off and saturation
• cut off and pinch-off
• 0 and IDSS
• pinch-off and breakdown

Q.15. At cut-off, the JFET channel is ……………

• at its widest point
• completely closed by the depletion region
• extremely narrow
• reverse biased

Answer: completely closed by the depletion region

Q.16. A MOSFET differs from a JFET mainly because ……………

• of power rating
• the MOSFET has two gates
• the JFET has a pn junction
• none of above

Answer: the JFET has a pn junction

Q.17. A certain D-MOSFET is biased at VGS = 0V. Its data sheet specifies IDSS = 20 mA and VGS (off) = – 5V. The value of the drain current is ……………

• 20 mA
• 0 mA
• 40 mA
• 10 mA

Q.18. An n-channel D-MOSFET with a positive VGS is operating in ……………

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

Q.19. A certain p-channel E-MOSFET has a VGS (th) = – 2V. If VGS = 0V, the drain current is ………

• 0 mA
• ID (on)
• maximum
• IDSS

Q.20. In a common-source JFET amplifier, the output voltage is ……………

• 180° out of phase with the input
• in phase with the input
• 90° out of phase with the input
• taken at the source

Answer: 180° out of phase with the input

Q.21. In a certain common-source D-MOSFET amplifier, Vds = 3.2 V r.m.s. and Vgs = 280 mV r.m.s. The voltage gain is ……………

• 1
• 11.4
• 8.75
• 3.2

Q.22. In a certain CS JFET amplifier, RD = 1 kΩ, RS = 560Ω, VDD = 10 V and gm = 4500 μS. If the source resistor is completely bypassed, the voltage gain is ……………

• 450
• 45
• 2.52
• 4.5

Q.23. 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: the voltage gain will decrease

Q.24. A CS JFET amplifier has a load resistance of 10 kΩ and RD = 820Ω. If gm = 5 mS and Vin = 500 mV, the output signal voltage is …

• 2.05 V
• 25 V
• 0.5 V
• 1.89 V