field effect transistors fet Mcqs
1. In a JFET, IDSS is known as ________________?
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A. none of the above

B. drain to source current

C. drain to source current with gate shorted

D. drain to source current with gate open

2. A JFET has high input impedance because _________________?
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A. of impurity atoms

B. none of the above

C. it is made of semiconductor material

D. input is reverse biased
3. The constant-current region of a JFET lies between______________?
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A. pinch-off and breakdown

B. cut off and saturation

C. cut off and pinch-off

D. and IDSS

4. A JFET is similar in operation to ___________ valve?
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A. triode

B. tetrode

C. pentode

D. diode

5. The gate of a JFET is ___________ biased?
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A. forward

B. reverse

C. none of the above

D. reverse as well as forward

6. 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 _____________?
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A. 20 mA

B. 0 mA

C. 40 mA

D. 10 mA

7. In a certain CS JFET amplifier, RD= 1kO , RS= 560 O , VDD=10V and gm= 4500 S. If the source resistor is completely bypassed, the voltage gain is ________________?
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A. 2.52

B. 45

C. 450

D. 4.5

8. A certain JFET data sheet gives VGS(off) = -4 V. The pinch-off voltage Vp is _____________?
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A. -4 V

B. data insufficient

C. +4 V

D. dependent on VGS

9. When drain voltage equals the pinch-off-voltage, then drain current ___________ with the increase in drain voltage?
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A. decreases

B. increases

C. none of the above

D. remains constant
10. The two important advantages of a JFET are _________________?
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A. inexpensive and high output impedance

B. none of the above

C. low input impedance and high output impedance

D. high input impedance and square-law property
11. In a p-channel JFET, the charge carriers are _____________?
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A. electrons

B. holes

C. both electrons and holes

D. none of the above

12. _____________ has the lowest noise-level?
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A. triode

B. tetrode

C. JFET

D. ordinary trnsistor

13. A MOSFET is sometimes called______________ JFET?
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A. open gate

B. many gate

C. insulated gate

D. shorted gate

14. The pinch-off voltage of a JFET is about _______________?
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A. 25 V

B. 0.6 V

C. 5 V

D. 15 V

15. A JFET is a__________ driven device?
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A. current

B. voltage

C. both current and voltage

D. none of the above

16. A n-channel D-MOSFET with a positive VGS is operating in _______________?
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A. the enhancement-mode

B. cut off

C. saturation

D. the depletion-mode

17. A MOSFET can be operated with________________?
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A. negative gate voltage only

B. positive gate voltage only

C. none of the above

D. positive as well as negative gate voltage
18. A JFET is also called____________ transistor?
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A. bipolar

B. unipolar

C. unijunction

D. none of the above

19. A JFET has three terminals, namely________________?
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A. emitter, base, collector

B. none of the above

C. cathode, anode, grid

D. source, gate, drain
20. A MOSFET uses the electric field of a _______________to control the channel current?
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A. battery

B. none of the above

C. generator

D. capacitor
21. n a common-source JFET amplifier, the output voltage is _____________?
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A. taken at the source

B. in phase with the input

C. 180o out of phase with the input

D. 90o out of phase with the input

22. If load resistance in the above question (Q.49) is removed, the output voltage will_____________?
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A. increase

B. stay the same

C. decrease

D. be zero

23. If the gate of a JFET is made less negative, the width of the conducting channel__________________?
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A. remains the same

B. is increased

C. none of the above

D. is decreased

24. In a JFET, when drain voltage is equal to pinch-off voltage, the depletion layers ______________?
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A. none of the above

B. have moderate gap

C. almost touch each other

D. have large gap

25. The input impedance of a MOSFET is of the order of______________?
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A. kO

B. several MO

C. O

D. a few hundred O

26. In a FET, there are _____________pn junctions at the sides?
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A. four

B. three

C. two

D. five

27. 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_______________?
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A. 8.75

B. 11.4

C. 1

D. 3.2

28. A certain common-source JFET has a voltage gain of 10. If the source bypass capacitor is removed, ______________?
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A. the voltage gain will increase

B. the Q-point will shift

C. the voltage gain will decrease

D. the transconductance will increase

29. The pinch-off voltage in a JFET is analogous to _____________ voltage in a vacuum tube?
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A. none of the above

B. anode

C. cathode

D. grid cut off
30. A MOSFET has______________ terminals?
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A. three

B. four

C. two

D. five

31. If the cross-sectional area of the channel in n-channel JEFT increases, the drain current _____________?
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A. is decreased

B. remains the same

C. is increased

D. none of the above

32. A CS JFET amplifier has a load resistance of 10 kO , RD= 820O . If gm= 5mS and Vin= 500 mV, the output signal voltage is__________________?
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A. 25 V

B. 1.89 V

C. 2.05 V

D. 0.5 V

33. Which of the following devices has the highest input impedance ?
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A. ordinary transistor

B. Crystal diode

C. JFET

D. MOSFET
34. A JFET has ____________ power gain?
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A. very small

B. small

C. very high

D. none of the above

35. The input control parameter of a JFET is __________________?
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A. drain voltage

B. source voltage

C. gate voltage

D. gate current

36. The output characteristics of a JFET closely resemble the output characteristics of a ___________ valve?
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A. tetrode

B. triode

C. diode

D. pentode
37. A MOSFET differs from a JFET mainly because _________________?
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A. the MOSFET has two gates

B. none of the above

C. the JFET has a pn junction

D. of power rating

38. A certain p-channel E-MOSFET has VGS(th) = -2V. If VGS= 0V, the drain current is ____________?
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A. ID(on)

B. IDSS

C. 0 mA

D. maximum

39. In class A operation, the input circuit of a JFET is ____________ biased?
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A. reverse

B. forward

C. not

D. none of the above

40. The transconductance of a JFET ranges from ________________?
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A. above 1000 mA/V

B. 100 to 500 mA/V

C. 0.5 to 30 mA/V

D. 500 to 1000 mA/V

41. The channel of a JFET is between the ________________?
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A. input and output

B. gate and source

C. gate and drain

D. drain and source
42. The source terminal of a JEFT corresponds to _____________ of a vacuum tube?
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A. grid

B. plate

C. cathode

D. none of the above

43. If the reverse bias on the gate of a JFET is increased, then width of the conducting channel ______________?
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A. is decreased

B. none of the above

C. is increased

D. remains the same

44. The gate voltage in a JFET at which drain current becomes zero is called ______________ voltage?
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A. cut-off

B. active

C. pinch-off

D. saturation

45. For VGS = 0 V, the drain current becomes constant when VDS exceeds ________________?
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A. cut off

B. V

C. VDD

D. VP
46. A common base configuration of a pnp transistor is analogous to _____________?of a JFET
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A. common gate configuration

B. common source configuration

C. common drain configuration

D. none of the above

47. At cut-off, the JFET channel is _____________?
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A. at its widest point

B. completely closed by the depletion region

C. reverse baised

D. extremely narrow