Power Electronics mcq - power electronics Multiple Choice Questions - Electrical input

Sunday, August 5, 2018

Power Electronics mcq - power electronics Multiple Choice Questions

                                                   Power Electronics mcq

power electronics multiple choice questions -

1.       A single phase full bridge inverter can operated in load commutation mode in case load consist of
            (a) RLC underdamped
                        (b) RLC critically damped
                  (c)  RLC
        (d)   RLC overdamped

          Ans – a

2.       The typical value of SCR for modern alternator is
(a)    0.5
(b)   1.0
(c)    1.5
(d)   2.0

3.       Which statement is true for latching current of the following  ---
(d)   It is related to turn on process of the device
(e)   It is related to turn off process of the device
(f)     It is related to conduction process of device
(g)    Both (a) and (b)

4.       The form factor for half wave rectified sine wave is—
(a)    1.45
(b)   1.51
(c)    1.57
(d)   1.61

5.       full-wave rectified sine wave, mean value is---
(a)    0.60im
(b)   0.61im
(c)    0.636im
(d)   0.386im
Ans ---c

6.       A thyratron is a ----
(a)    gas-filled triode
(b)   vacuum tube with four electrodes
(c)    gas-filled diode
(d)   all of the above
Ans –a

Q.. silicon controlled rectifier is  ---
(a)    Device with two junctions
(b)   Unijunction
(c)    Device with three junction
(d)   All of the above

7.       a waveform more peaky than a sine wave, the form factor will be—
(a)    1
(b)   11
(c)    More than 1.11 %
(d)   Less than 1.11 %

8.       Thyristor can be protected from over voltages by using ------
(a)    heat sink
(b)   voltage clamping device
(c)    fuse
(d)   relay

9.       Under normal operating voltage clamping device offers impedance of ---
(a)    Infinity
(b)   Low value
(c)    High value
(d)   Zero
Ans---- a

10.   What is used to protect the SCR from over current ---
(a)    CB and fuse
(b)   Snubber circuit
(c)    Voltage clamping device
(d)   Heat sink
Ans --- a

11.   A crystal diode has ----
(a)    One pn junction
(b)   Two pn junction
(c)    Three pn junction
(d)   All of the above
Ans ---- a

12.   A zener diode has----
(a)    One pn junction
(b)   Two pn junction
(c)    Three pn junction
(d)   All of the above
Ans--- a

13.   zener diode is used as ----
(a)    an amplifier
(b)   a rectifier
(c)    voltage regulation
(d)   multivibrator
Ans--- c

14.   zener diode is alwa connected-----
(a)    forward
(b)   reverse
(c)    both (a) and (b)
(d)   none of the above

15.   which of the following rectifier has the lowest forward resistance---
(a)    Gas tube
(b)   Vaccume tube
(c)    Solid State
(d)   None

16.   There is a need of transformer for-----
(a)    Bridge full wave rectifier
(b)   Centre tap full wave rectifier
(c)    Half wave rectifier
(d)   None of above
Ans ----b

17.   What happened. if the PIV rating of a diode is exceeded----
(a)    Diode is destroyed
(b)   Diode conduct poorly
(c)    Diode behaves like zener diode
(d)   None

18.   Max efficiency of a half-wave rectifier is ----
(a)    25%
(b)   40.6%
(c)    70%
(d)   100%
Ans ---b

19.   Most widely used rectifier is -----
(a)    Half wave rectifier
(b)   Full wave rectifier
(c)    Centre tap full wave rectifier
(d)   Bridge full wave rectifier
Ans---- 3

20.   When transistor are used  in the circuit they usually operate in the---
(a)    Breakdown region
(b)   Active region
(c)    Saturation and cutoff
(d)   Linear region
Ans ---- c

21.   The gate of a junction gate field effect transistor (JFET) is ------------ biased
(a)    Forward
(b)   Reverse
(c)    Both (a) and (b)
(d)   None of the above

22.   The charge carrier are in a p channel JFET -------
(a)    Holes
(b)   Electrons
(c)    Both (a) and (b)
(d)   None

23.   MOSFET (metal oxide semiconductor field effect transistor) has _______  terminal
(a)    1
(b)   2
(c)    3
(d)   4
Ans -----d

(a)    Impedance gate bipolar transistor
(b)   Integrated gate bipolar transistor
(c)    Insulated gate bipolar transistor
(d)   Indicating gate bipolar transistor
Ans --- c

25.   HBT Full Form ------
(a)    Hexajunction bipolar transistor
(b)    Heterojunction bipolar transistor
(c)    Hexadecimal bipolar transistor
(d)   Herojunction bipolar transistor

26.   In class A operation, the input circuit of a JFET is ………. Biased
(a)    Reverse
(b)   Forward
(c)    Both (a) and (b)
(d)   None of the above

27.   The channel of a JFET is between the -----
(a)    Gate and source
(b)   Gate and drain
(c)    Input and output
(d)   Drain and source

28.   JFET has three terminals, namely-------
(a)source , gate , drain
(b) cathode, anode , grid
(c ) emmiter , base , collector
Ans ---- a

29.   JFET is also called______- transistor
(a)    Bipolar
(b)   Unipolar
(c)    Unijunction
(d)   None
Ans --- b

30.   The input control parameter of a JFET is---
(a)    Source voltage
(b)   Gate voltage
(c)    Drain voltage
(d)   Gate current
Ans --- b

31.   basically termed as normally-OFF MOSFET works only with----
(a)    large negative drain voltage
(b)   large positive gate voltage
(c)    large positive drain voltage
(d)   large negative gate voltage
Ans ---b

32.   IGBT possess ----
(a)    high input impedance
(b)   high on-state resistance
(c)    low input impedance
(d)   All of the above
Ans--- a

33.   controlling parameter in IGBT -----
(a) IC
(b) VGE
(c) Vce
(d) IG

Ans ----- b

34.   Which terminal does not belong to the SCR –
(a)    Anode
(b)   Cathode
(c)    Gate
(d)   Base
Ans--- d

35.   thyristor (SCR) is a---
(a)    NPN
(b)   PNP
(c)    PNPN
(d)   PN
Ans----  PNPN ©

36.   power transistor is a ----
(a)    two layer, one junction device
(b)   three layer, two junction device
(c)    three layer, three junction device
(d)   four layer, three junction device
Ans --- b

37.   GTO (gate turn-off thyristor) is a ---
(a)    PNP
(b)   PNPN
(c)    P-METAL –N – DEVICE
Ans---- b

38.   The latching current is___ than the holding current
(a)    Negative
(b)   Lower
(c)    Higher
(d)   Same as
Ans--- b

39.   Schottky diodes are also known as -------
(a)    signaling diode
(b)   easy turn on diode
(c)    hot carrier diode
(d)   metal diode
Ans ---- c


  1. In Question no. 38 ., Sir as per my knowledge latching current is 2-3 times of holding current
    so latching current is grater than holding current

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