MCQ on Power electronics – 1

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 1. Chopper is also known as
(A) AC transfromer.
(B) DC transformer.
(C) voltage changer.
(D) voltage reducer.

 2. A thyristor can be termed as
(A) AC switch.
(B) DC switch.
(C) both AC and DC switch.
(D) square wave switch.

 3. Which of the following semiconductor power device is not a current triggered device
(A) SCR.
(B) GTO.

 4. IGBT is a modern power semiconductor device, that combine the characteristics of
(A) BJT and SCR.
(D) GTO and Thyristor.

 5. Which of the following power electronic device can be used for high frequency switching application?
(A) BJT.
(B) Power MOSFET.
(C) Schottky diode.
(D) Microwave transistor.

 6. In a 3 phase fully controlled converter the firing frequency is
(A) 3 times the line frequency.
(B) 6 times the line frequency.
(C) 9 times the line frequency.
(D) 12 times the line frequency.

 7. Thyristor can be protected from over voltages by using
(A) voltage clamping device.
(B) fuse.
(C) heat sink.
(D) snubber circuit.

 8. Turn on and turn off times of transistor depends on
(A) applied voltage.
(B) current gain.
(C) junction capacitance.
(D) applied frequency.

 9. A thyristor controlled reactor is used to get
(A) variable resistance.
(B) variable capacitance.
(C) variable inductance.
(D) improved reactive power factor.

 10. A semiconductor device which act like a diode and two transistors is
(C) UJT.

 11. UJT is known as
(A) voltage controlled device.
(B) current controlled device.
(C) relaxation oscillator.
(D) triggered device.

 12. A thyristor can termed as
(A) ac switches.
(B) dc switches.
(C) both ac and dc switches.
(D) square wave switches.

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