FET – Exercise – 1

1. The JFET acts as a ……….. along vertical parts of the drain curve.

(a)  Resistor
(b)  Current source
(c)  Voltage source
(d)  Current sink

Answer
Answer : (a)
Explanation
No answer description available for this question. Let us discuss.
2. The transconductance curve of JFET which is also called as square law curve is :

(a)  Straight line
(b)  Parabolic
(c)  Circular
(d)  Wavy

Answer
Answer : (b)
Explanation
No answer description available for this question. Let us discuss.
3. Which of the following is/are valid statement(s) ?
1. The gate of a JFET is forward biased hence acts as a voltage controlled device.
2. The gate of a JFET is reversed biased, hence acts as a voltage controlled device.
3. The gate of a JFET is reverse biased, hence acts as voltage controlled device.

(a)  1
(b)  2
(c)  1 and 2
(d)  1, 2 and 3

Answer
Answer : (b)
Explanation
No answer description available for this question. Let us discuss.
4. Field effect transistor has :

(a)  large input impedance
(b)  large output impedance
(c)  large power gain
(d)  large voltage gain

Answer
Answer : (a)
Explanation
No answer description available for this question. Let us discuss.
5. In the voltage range, Vp < VDS< BVDSS of an ideal JFET or MOSFET :

(a)  the drain current varies linearly with VDS
(b)  the drain current is constant
(c)  the drain current varies non-linearly with VDS
(d)  the drain current is cut off

Answer
Answer : (b)
Explanation
No answer description available for this question. Let us discuss.
6. The transconductance, gm of a JFET is computed at constant VDS, by the following :

(a)  ∆ID/∆VGS
(b)  ∆VGS/∆ID
(c)  ∆VGSx∆ID
(d)  ∆ID/∆VGS+∆IDS

Answer
Answer : (a)
Explanation
No answer description available for this question. Let us discuss.
7. The pinch-off voltage of JFET has a same magnitude as that of :

(a)  Gate voltage
(b)  Gate source voltage
(c)  Drain–source voltage
(d)  None of these

Answer
Answer : (a)
Explanation
No answer description available for this question. Let us discuss.
8. The gate cut-off and pinch-off voltages of JFET have :

(a)  Same magnitude and sign
(b)  Different magnitudes but same sign
(c)  Same magnitude but different signs
(d)  Different magnitudes and signs

Answer
Answer : (c)
Explanation
No answer description available for this question. Let us discuss.
9. The output characteristics of a JFET is similar to :

(a)  Triode
(b)  Pentode
(c)  Thyratron
(d)  Tetrode

Answer
Answer : (b)
Explanation
No answer description available for this question. Let us discuss.
10. For small values of drain to source voltage, JFET behaves like a :

(a)  Diode
(b)  Capacitor
(c)  Inverter
(d)  Resistor

Answer
Answer : (d)
Explanation
No answer description available for this question. Let us discuss.
(a) (b) (c) (d) Answer : () [/su_spoiler]
Explanation
No answer description available for this question. Let us discuss.
12. With reference to JFET configuration, match the following
(P) Common Source Configuration         (1) No phase shift between input & output
(Q) Common Drain Configuration           (2) High input impedance & low output impedance
(R) Common Gate Configuration             (3) Source follower Configuration

(a)  P-1, Q-2, R-3
(b)  P-2, Q-3, R-1
(c)  P-2, Q-1, R-3
(d)  P-3, Q-1, R-2

Answer
Answer : (b)
Explanation
No answer description available for this question. Let us discuss.
13. Conduction modulation is exhibited by :

(a)  Transistor
(b)  Diode
(c)  JFET
(d)  Tunnel diode

Answer
Answer : (c)
Explanation
No answer description available for this question. Let us discuss.
14. Junction gate type of FET can be operated :

(a)  Only in depletion mode
(b)  Only in enhancement mode
(c)  Both depletion & enhancement modes
(d)  Either depletion or enhancement mode

Answer
Answer : (a)
Explanation
No answer description available for this question. Let us discuss.
15. The constant current area of FET lies between :

(a)  0 & IDSS
(b)  Cut off & Pinch off regions
(c)  Cut off & Saturation regions
(d)  Pinch-off & break-down regions

Answer
Answer : (d)
Explanation
No answer description available for this question. Let us discuss.
16. A BJT is …….. controlled and the FET is ………. controlled device.

(a)  Current, Current
(b)  Voltage, Voltage
(c)  Voltage, Current
(d)  Current, Voltage

Answer
Answer : (d)
Explanation
No answer description available for this question. Let us discuss.
17. The gate of FET is analogous to the …….. of BJT.

(a)  Emitter
(b)  Collector
(c)  Base
(d)  None of these

Answer
Answer : (b)
Explanation
No answer description available for this question. Let us discuss.
18. The equivalent circuit of FET contains :

(a)  A current source in series with resistance
(b)  A resistance between drain and source terminals
(c)  A current source between gate and source terminals
(d)  A current source between drain and source terminals

Answer
Answer : (d)
Explanation
No answer description available for this question. Let us discuss.
19. Which of the following statements is/are correct ?
1. The input capacitance of FET is low.
2. The transfer characteristics of FET can be represented mathematically by the Shockley equation.

(a)  Statement 1
(b)  Statement 2
(c)  Both statements 1 & 2
(d)  Either statement 1 or 2

Answer
Answer : (c)
Explanation
No answer description available for this question. Let us discuss.
20. In an ideal JFET, RGS is infinite because :

(a)  IG< 0
(b)  IG> 0
(c)  IG= 0
(d)  IG= ∞

Answer
Answer : (c)
Explanation
No answer description available for this question. Let us discuss.
21. Which is valid with respect to JFET ?

(a)  Operated in depletion and enhancement modes
(b)  Gate is not insulated from channel
(c)  Channel doesn’t permanently exist
(d)  It possesses low input impedance

Answer
Answer : (b)
Explanation
No answer description available for this question. Let us discuss.
22. An n-channel JFET having a pinch off voltage of –5 V shows a transconductance of 1 mA/V when applied gate-to-source voltage of –3 V. Then its maximum transconductance is found to be :

(a)  1.5 mA/V
(b)  2.0 mA/V
(c)  2.5 mA/V
(d)  3.0 mA/V

Answer
Answer : (c)
Explanation
No answer description available for this question. Let us discuss.
23. JFET channel is pinched-off only when :

(a)  VDD is equal to VP
(b)  VDSis greater than VP
(c)  VDSis less than VP
(d)  VDSis equal to VP

Answer
Answer : (d)
Explanation
No answer description available for this question. Let us discuss.
24. Determine the invalid statement.

(a)  For an n-channel JFET, both VGS and VP are negative
(b)  For a p-channel JFET, both VGS and VP are positive
(c)  For an n-channel JFET, IDSS is positive
(d)  For a p-channel JFET, IDSS is positive

Answer
Answer : (d)
Explanation
No answer description available for this question. Let us discuss.
25. An FET acts as :

(a)  A variable resistor
(b)  A variable capacitor
(c)  A variable voltage source
(d)  A variable current source

Answer
Answer : (d)
Explanation
No answer description available for this question. Let us discuss.
26. Consider the statements given below :
Statement I : In FET the generator current is proportional to the input voltage.
Statement II : In BJT, the generator current is proportional to the input current.
Which of the following is valid ?

(a)  Statement I
(b)  Statement II
(c)  Both statements I & II
(d)  Either statement I or II

Answer
Answer : (c)
Explanation
No answer description available for this question. Let us discuss.
27. FETs are used in an amplifier to obtain :

(a)  Low input impedance
(b)  Low output impedance
(c)  High input impedance
(d)  High output impedance

Answer
Answer : (c)
Explanation
No answer description available for this question. Let us discuss.
28. Which of the following exhibits very high input impedance ?

(a)  Diode
(b)  P-N-P
(c)  N-P-N
(d)  FET

Answer
Answer : (d)
Explanation
No answer description available for this question. Let us discuss.
29. …….. indicates how effectively the input voltage controls the output current in a JFET.

(a)  Slow rate
(b)  Transconductance
(c)  Transresistance
(d)  Intrinsic stand-off ratio

Answer
Answer : (b)
Explanation
No answer description available for this question. Let us discuss.
30. ……… is preferred form of bias for a JFET amplifier.

(a)  Self bias
(b)  Voltage divider bias
(c)  Two supply bias
(d)  Emitter feedback bias

Answer
Answer : (a)
Explanation
No answer description available for this question. Let us discuss.
31. The transconductance JFET at the Q-point is ……… the maximum transconductance which occurs when Vds = 0.

(a)  Less than
(b)  Greater than
(c)  Equal to
(d)  None of the above

Answer
Answer : (a)
Explanation
No answer description available for this question. Let us discuss.
32. A current regulator diode is basically a :

(a)  Zener diode
(b)  MOSFET
(c)  JFET whose gate and source are tied up
(d)  Transistor

Answer
Answer : (c)
Explanation
No answer description available for this question. Let us discuss.
33. A JFET has :

(a)  One built-in diode
(b)  Two built-in diodes
(c)  Three built-in diodes
(d)  Four built-in diodes

Answer
Answer : (b)
Explanation
No answer description available for this question. Let us discuss.
34. The JFET acts as a …….. along the horizontal part of the drain curve.

(a)  Resistor
(b)  Current source
(c)  Voltage source
(d)  Current sink

Answer
Answer : (b)
Explanation
No answer description available for this question. Let us discuss.
35. Which of the following is/are valid statement(s) ?
I. The gate of a JFET is forward biased hence acts as a voltage controlled device.
II. The gate of a JFET is reversed biased, hence acts as a voltage controlled device.
III. The gate of a JFET is reverse biased, hence acts as voltage controlled device.

(a)  I
(b)  II
(c)  I and II
(d)  I, II and III

Answer
Answer : (b)
Explanation
No answer description available for this question. Let us discuss.
36. FET has offset voltage of about :

(a)  0.2 volts
(b)  0.6 volts
(c)  1.0 volts
(d)  3.6 volts

Answer
Answer : (c)
Explanation
No answer description available for this question. Let us discuss.
37. The point above the drain voltage, where there is no increase in drain current in a JFET is called as :

(a)  Breakdown point
(b)  Pinch off point
(c)  Knee point
(d)  Critical point

Answer
Answer : (b)
Explanation
No answer description available for this question. Let us discuss.
38. A JFET has three terminals, namely …….

(a)  cathode, anode, grid
(b)  emitter, base, collector
(c)  source, gate, drain
(d)  none of the above

Answer
Answer : (c)
Explanation
No answer description available for this question. Let us discuss.
39. A JFET is similar in operation to ……. valve.

(a)  diode
(b)  pentode
(c)  triode
(d)  tetrode

Answer
Answer : (b)
Explanation
No answer description available for this question. Let us discuss.
40. A JFET is also called ……. transistor.

(a)  unipolar
(b)  bipolar
(c)  unijunction
(d)  none of the above

Answer
Answer : (a)
Explanation
No answer description available for this question. Let us discuss.
41. A JFET is a ……. driven device.

(a)  current
(b)  voltage
(c)  both current and voltage
(d)  none of the above

Answer
Answer : (b)
Explanation
No answer description available for this question. Let us discuss.
42. The gate of a JFET is ……. biased.

(a)  reverse
(b)  forward
(c)  reverse as well as forward
(d)  none of the above

Answer
Answer : (a)
Explanation
No answer description available for this question. Let us discuss.
43. The input impedance of a JFET is ……. that of an ordinary transistor.

(a)  equal to
(b)  less than
(c)  more than
(d)  none of the above

Answer
Answer : (c)
Explanation
No answer description available for this question. Let us discuss.
44. In a p-channel JFET, the charge carriers are …….

(a)  electrons
(b)  holes
(c)  both electrons and holes
(d)  none of the above

Answer
Answer : (b)
Explanation
No answer description available for this question. Let us discuss.
45. A JFET……… is usually the point of reference.

(a)  Gate
(b)  Drain
(c)  Source
(d)  Either b or c

Answer
Answer : (c)
Explanation
No answer description available for this question. Let us discuss.
46. The input gate current of a FET is :

(a)  A few amperes
(b)  A few milliamperes
(c)  A few micro amperes
(d)  Negligibly small

Answer
Answer : (d)
Explanation
No answer description available for this question. Let us discuss.
47. When drain voltage equals the pinch-off voltage, then drain current ……. with the increase in drain voltage.

(a)  decreases
(b)  increases
(c)  remains constant
(d)  none of the above

Answer
Answer : (c)
Explanation
No answer description available for this question. Let us discuss.
48. If the reverse bias on the gate of a JFET is increased, then width of the conducting channel …….

(a)  is decreased
(b)  is increased
(c)  remains the same
(d)  none of the above

Answer
Answer : (a)
Explanation
No answer description available for this question. Let us discuss.
49. A JFET has ……. power gain.

(a)  small
(b)  very high
(c)  very small
(d)  none of the above

Answer
Answer : (b)
Explanation
No answer description available for this question. Let us discuss.
50. The input control parameter of a JFET is …….

(a)  gate voltage
(b)  source voltage
(c)  drain voltage
(d)  gate current

Answer
Answer : (a)
Explanation
No answer description available for this question. Let us discuss.