Power electronics MCQ #5

1) The UJT may be used as ________

       (A) Amplifier

       (B) A sawtooth generator

       (C) A rectifier

       (D) None of the above

2) In a single-phase full wave regulator, the firing angles in the positive and negative half cycles are generally

       (A) equal

       (B) different

       (C) equal or different

       (D) different but sometimes equal

3) The terminals of a power BJT are called

       (A) emitter, base, collector

       (B) emitter, base, drain

       (C) source, base, drain

       (D) source, base, collector

4) In single phase half wave regulator, the average current over one full cycle

       (A) is always positive

       (B) may be positive or negative

       (C) may be negative

       (D) is always negative

5) The terminals of a power MOSFET are called

       (A) emitter, base, collector

       (B) source, gate, drain

       (C) source, base, drain

       (D) emitter, gate, drain

ANSWER: | 1-b | 2-a | 3-a | 4-d | 5-b |

6) In a thyristor the gate current is increased, then

       (A) anode current will increase

       (B) anode current will decrease

       (C) anode current will remain constant

       (D) anode current may increase or decrease

7) A TRIAC is equivalent to two SCRs________

       (A) In parallel

       (B) In series

       (C) In inverse-parallel

       (D) None of the above

8) A TRIAC is a _______ Switch

       (A) Bidirectional

       (B) Unidirectional

       (C) Mechanical

       (D) None of the above

9) which of the following device does not have the gate terminal is?

       (A) TRIAC

       (B) FET

       (C) SCR

       (D) DIAC

10) A UJT has ________

       (A) Two pn junctions

       (B) One pn junction

       (C) Three pn junctions

       (D) None of the above

ANSWER: | 6-c | 7-c | 8-a | 9-d | 10-b |

11) A UJT is sometimes called ________ Diode

       (A) Low resistance

       (B) High resistance

       (C) Single-base

       (D) Double-base

12) A DIAC is turned on by _________

       (A) A breakover voltage

       (B) Gate voltage

       (C) Gate current

       (D) None of the above

13) Which of the following is not a characteristic of UJT?

       (A) Intrinsic standoff ratio

       (B) Negative resistance

       (C) Peak-point voltage

       (D) Bilateral conduction

14) After peak point, the UJT operates in the ________ Region

       (A) Cut-off

       (B) Saturation

       (C) Negative resistance

       (D) None of the above

15) A DIAC is simply ________

       (A) A single junction device

       (B) A three-junction device

       (C) A TRIAC without gate terminal

       (D) None of the above

ANSWER: | 11-d | 12-a | 13-d | 14-c | 15-c |

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