Power Electronics – MCQs

1. : What is the main function of a power electronic converter?
(A) Signal amplification
(B) Power conversion
(C) Frequency modulation
(D) Data transmission

2. : Which device is commonly used in power electronics for switching applications?
(A) BJT
(B) MOSFET
(C) SCR
(D) All of the above

3. : The full form of SCR is:
(A) Silicon Controlled Rectifier
(B) Semiconductor Controlled Regulator
(C) Simple Current Relay
(D) Solid Capacitor Resistor

4. : Which one of these is a unidirectional device?
(A) Diode
(B) TRIAC
(C) MOSFET
(D) IGBT

5. : A TRIAC can conduct current in:
(A) Only forward direction
(B) Only reverse direction
(C) Both directions
(D) Alternating cycles only

6. : What is the typical application of a chopper in power electronics?
(A) AC to DC conversion
(B) DC to DC voltage regulation
(C) Frequency control
(D) Data communication

7. : Inverters convert:
(A) AC to DC
(B) DC to AC
(C) AC to AC
(D) DC to DC

8. : The operation of a power MOSFET is based on:
(A) Junction principle
(B) Field-effect principle
(C) Bipolar operation
(D) Thermionic emission

9. : Which device combines the advantages of BJT and MOSFET?
(A) SCR
(B) TRIAC
(C) IGBT
(D) UJT

10. : What is the main drawback of SCR in switching circuits?
(A) Cannot handle high voltages
(B) Cannot be turned off by gate signal
(C) Low current rating
(D) Expensive

11. : The firing angle of an SCR is defined as:
(A) Time when the SCR turns off
(B) Time when the anode current drops
(C) Time from zero voltage to the gate trigger
(D) Time from zero crossing to when gate signal is applied

12. : Which converter converts AC of one frequency to AC of another frequency?
(A) Chopper
(B) Inverter
(C) Cycloconverter
(D) Rectifier

13. : In a full-wave rectifier, the number of diodes used is:
(A) 1
(B) 2
(C) 3
(D) 4

14. : The advantage of using IGBT over MOSFET is:
(A) Lower cost
(B) Faster switching
(C) Higher voltage handling
(D) Lower gate drive

15. : A snubber circuit is used in power electronics to:
(A) Reduce noise
(B) Control temperature
(C) Protect device from voltage spikes
(D) Increase power output

16. : Which of the following is an uncontrolled device?
(A) SCR
(B) Diode
(C) TRIAC
(D) IGBT

17. : Which material is commonly used for high-power semiconductor devices?
(A) Germanium
(B) Gallium Arsenide
(C) Silicon
(D) Copper

18. : The term “commutation” in SCRs refers to:
(A) Turning ON
(B) Turning OFF
(C) Increasing frequency
(D) Boosting current

19. : A buck converter is used to:
(A) Increase DC voltage
(B) Decrease DC voltage
(C) Convert AC to DC
(D) Convert DC to AC

20. : The main drawback of a linear voltage regulator is:
(A) High efficiency
(B) Simple design
(C) Heat dissipation
(D) Low cost

21. : The basic component of a PWM-based inverter is:
(A) Transformer
(B) Inductor
(C) Switch (like MOSFET/IGBT)
(D) Capacitor

22. : A boost converter increases:
(A) Current
(B) Frequency
(C) Voltage
(D) Power loss

23. : In a three-phase inverter, the number of switching devices required is:
(A) 2
(B) 4
(C) 6
(D) 8

24. : Which power electronic device is suitable for fast switching applications?
(A) SCR
(B) TRIAC
(C) IGBT
(D) MOSFET

25. : The efficiency of power electronic devices is generally:
(A) Below 50%
(B) Between 60–70%
(C) Above 85%
(D) Exactly 100%