Power Semiconductors Solved Objective Questions: Part-I

[1] Which of the following statements are correct?

1. Thyristor is current driven device

2. GTO is current driven device

3. GTR is current driven device

4. SCR is a pulse triggered device

(a) 1 and 2
(b)1, 2, 3
(c) All
(d) 4 only

Ans:C

[2] Which of the following statements are correct?

1.  GTO is a pulse triggered device

2.  MOSFET is uni-polar device

3.  SCR is a bipolar device

4.  Continuous gate signal is not required to maintain the SCR to be in ON state

(a)  1, 2, 4 only

(b)  1, 2 only

(c)  4 only

(d)  All

Ans: D

[3] Which of the following is not a fully controlled semiconductor device?

(a) MOSFET

(b) IGBT

(c) IGCT

(d) SCR

Ans: D . Only turn on of the SCR can be controlled whereas in other devices we can control both turn on and turn off

[4] Which of the following is not associated with p-n junction

(a) Junction capacitance

(b) Charge storage capacitance

(c) Depletion capacitance

(d) Channel length modulation

Ans: D

[5] In a p-n junction diode under reverse bias, the magnitude of electric field is maximum at

(a) The edge of the depletion region on the P-side

(b) The edge of the depletion region on the N-side

(c) The P-N junction

(d) The center of the depletion region on the N-side

Ans: C

[6] An n-channel JFET has IDSS=2mA, and Vp=-4V. Its transconductance gm=(in mA/V) for an applied gate to source voltage VGS=-2V is

(a) 0.25

(b) 0.5

(c) 0.75

(d)  1

Ans: B

[7] The MOSFET switch in its on-state may be considered equivalent to

(a) Resistor
(b) Inductor
(c) Capacitor
(d) Battery

Ans: C

[8] The effective channel length of a MOSFET in a saturation decreases with increase in
(a) Gate voltage
(b) Drain voltage
(c) Source voltage
(d) Body voltage

Ans:B

[9] The early effect in a bipolar junction transistor is caused by
(a) Fast turn - on
(b) Fast turn - off
(c) Large collector - base reverse bias
(d) Large emmiter - base forward bias

Ans: C

[10] MOSFET can be used as a
(a) Current controlled capacitor
(b) Voltage controlled capacitor
(c) Current controlled inductor
(d) Voltage controlled inductors

Ans: B

[11] The number of PN junctions in a SCR is
(a) 1
(b) 2
(c) 3
(d) 4

Ans: C

[12] In the SCR, when the anode terminal is positive with respect to cathode terminal, the number of blocked PN junctions is
(a) 1
(b) 2
(c) 3
(d) 4

Ans: A

[13] In the SCR, when the cathode terminal is positive with respect to anode terminal, the number of blocked PN junctions is
(a) 1
(b) 2
(c) 3
(d) 4

Ans: B

[14] In the SCR, the anode current is made up of
(a) Electrons only
(b) Electrons or holes
(c) Electrons and holes
(d) Holes only

Ans:C

[15] When the SCR is triggered, it will change from forward blocking state to conduction state if its anode to cathode voltage is equal to 
(a) Peak repetitive off-state forward voltage
(b) Peak working off-state forward voltage
(c) Peak working off-state reverse voltage
(d) Peak non-repetitive off-state forward voltage

Ans: B

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