Power Electronics MCQs

Option A: Only at turn – on

Option B: Only at turn – off

Option C: Both at turn on and off

Option D: None of these

Correct Answer: Both at turn on and off ✔

Option A: Do not contribute to the collector current

Option B: Result in net current flow component into the base

Option C: Contribute to the collector current

Option D: Only (a) and (b)

Correct Answer: Only (a) and (b) ✔

Option A: Is equal to the source resistance

Option B: Greater than the source resistance

Option C: Smaller than the source resistance

Option D: None of these

Correct Answer: Is equal to the source resistance ✔

Option A: Negative resistance characteristics

Option B: Goes into avalanche condition

Option C: Voltage drop snaps back

Option D: All of these

Correct Answer: All of these ✔

Option A: Decrease with frequency

Option B: Remains same with change in frequency

Option C: Increase with frequency

Option D: Either A. or B.

Correct Answer: Increase with frequency ✔

Option A: TRIAC

Option B: SCR

Option C: GTO

Option D: Only (a) and (b)

Correct Answer: Only (a) and (b) ✔

Option A: Diode and capacitor

Option B: Capacitor and SCR

Option C: Inductor and capacitor

Option D: Capacitor and load

Correct Answer: Diode and capacitor ✔

Option A: Equal to the input frequency

Option B: Twice the input frequency

Option C: Three times the input frequency

Option D: Six times the input frequency

Correct Answer: Six times the input frequency ✔

Option A: Symmetric triangular voltage across itself

Option B: Symmetric rectangular voltage across itself

Option C: Symmetric trapezoidal voltage across itself

Option D: Symmetric sinusoidal voltage across itself

Correct Answer: Symmetric trapezoidal voltage across itself ✔

Option A: Phase current

Option B: Three times the phase current

Option C: Three times the line current

Option D: Zero at all times

Correct Answer: Zero at all times ✔

Option A: Voltage across the commutating inductances collapses

Option B: The capacitance voltage adds to the supply voltage

Option C: Both A. and B.

Option D: None of these

Correct Answer: C. Both A. and B. ✔

Option A: Single phase

Option B: 3 phase

Option C: Poly phase

Option D: Only (b) and (c)

Correct Answer: Only (b) and (c) ✔

Option A: 61%

Option B: 71%

Option C: 81%

Option D: 91%

Correct Answer: 81% ✔

Option A: Line integrated stabilization network

Option B: Line impedance stabilization network

Option C: Line integrated stored network

Option D: Laser integrated stabilization networking

Correct Answer: Line impedance stabilization network ✔

Option A: V m

Option B: 2 V m

Option C: V m / 2

Option D: 4 V m

Correct Answer: V m ✔

Option A: rectifier

Option B: inverter

Option C: chopper

Option D: regulator

Correct Answer: rectifier ✔

Option A: Actual gain of amplifier

Option B: Actual gain of amplifier and attenuator

Option C: Gain in dB of amplifier and attenuator

Option D: Actual gain of attenuator

Correct Answer: Actual gain of amplifier ✔

Option A: anode current decreases

Option B: anode current does not decrease at all

Option C: anode current increases

Option D: cathode current increases

Correct Answer: anode current does not decrease at all ✔

Option A: Always positive w.r.t cathode

Option B: Always negative w.r.t anode

Option C: Always positive w.r.t anode

Option D: Always negative w.r.t cathode

Correct Answer: Always positive w.r.t cathode ✔

Option A: silicon has large leakage current than germanium

Option B: silicon has small leakage current than germanium

Option C: silicon has small leakage voltage than germanium

Option D: silicon has large leakage voltage than germanium

Correct Answer: silicon has small leakage current than germanium ✔

Option A: Across anode

Option B: In series with anode

Option C: Across cathode

Option D: In series with cathode

Correct Answer: In series with anode ✔

Option A: Two SCR’s in parallel opposition

Option B: Two SCR’s in series

Option C: Three SCR’s in series

Option D: Four SCR’s in series

Correct Answer: Two SCR’s in parallel opposition ✔

Option A: Two

Option B: Three

Option C: Four

Option D: Five

Correct Answer: Three ✔

Option A: Duty ratio only

Option B: Frequency only

Option C: Duty ratio and frequency

Option D: Duty ratio, frequency and time delay

Correct Answer: Duty ratio, frequency and time delay ✔

Option A: Insulated gate bipolar transistor

Option B: Insulated gate bidirectional transistor

Option C: Inductive gate bipolar transistor

Option D: Inductive gate bidirectional transistor

Correct Answer: Insulated gate bipolar transistor ✔

Option A: Electrical power developed in armature – copper losses

Option B: Mechanical power input – iron and friction losses

Option C: Electrical power developed in armature – iron and copper losses

Option D: Mechanical power input – iron and friction losses – copper losses

Correct Answer: Mechanical power input – iron and friction losses ✔

Option A: Lossless

Option B: Carry current in any direction when it is on

Option C: Does not carry any current in any direction when it is off

Option D: All of these

Correct Answer: All of these ✔

Option A: Zero

Option B: Non zero

Option C: Equal to the sum of voltage when switch is open

Option D: Twice of the voltage when switch is open

Correct Answer: Non zero ✔

Option A: It will rotate at the same speed as that with its field winding closed

Option B: It will rotate at less speed as that with its field winding closed

Option C: It will rotate at dangerously high speed

Option D: None of these

Correct Answer: It will rotate at dangerously high speed ✔

Option A: Indirect switch matrix circuits

Option B: Direct switch matrix circuits

Option C: Embedded converters

Option D: All of these

Correct Answer: Direct switch matrix circuits ✔

Option A: High speed operation

Option B: High rupturing capacity

Option C: No ageing effect

Option D: All of the above

Correct Answer: All of the above ✔

Option A: Load survey method

Option B: Mathematical method

Option C: Statistical method

Option D: Economic parameters

Correct Answer: Statistical method ✔

Option A: 0.75

Option B: 0.7

Option C: 0.2

Option D: 0.25

Correct Answer: 0.2 ✔

Option A: AC – AC converters

Option B: AC – DC converters

Option C: DC – AC converters

Option D: DC – DC converters

Correct Answer: D. DC – DC converters ✔

Option A: equal division of voltage across each thyristor

Option B: equal division of current through each thyristor in parallel

Option C: equal division of voltage across each thyristor in parallel

Option D: equal division of current through each thyristor in series

Correct Answer: equal division of voltage across each thyristor ✔

Option A: 60

Option B: 70

Option C: 80

Option D: 90

Correct Answer: 80 ✔

Option A: 76.3 %

Option B: 91.6 %

Option C: 83.3 %

Option D: 90.9 %

Correct Answer: 76.3 % ✔

Option A: Directly proportional to Vm of supply voltage

Option B: Inversely proportional to Vm of supply voltage

Option C: Inversely proportional to L in the circuit

Option D: Both A and C

Correct Answer: Directly proportional to Vm of supply voltage ✔

Option A: 5, 7

Option B: 4, 6

Option C: 7, 5

Option D: 6, 4

Correct Answer: 7, 5 ✔

Option A: R and C in series but with diode across C

Option B: R and C in series but with diode across R

Option C: Series R and diode with C across R

Option D: Series R and diode with C across R

Correct Answer: R and C in series but with diode across R ✔

Option A: String efficient

Option B: Reliability factor

Option C: Factor of safety

Option D: Derating factor

Correct Answer: Derating factor ✔

Option A: holes only

Option B: electrons only

Option C: either electron or holes

Option D: Both electron and holes

Correct Answer: holes only ✔

Option A: series connection.

Option B: parallel connection.

Option C: anti parallel connection.

Option D: both B and C.

Correct Answer: parallel connection. ✔

Option A: To limit di / dt of SCR

Option B: To limit dV / dt of SCR

Option C: For voltage equalisation

Option D: Both B and C

Correct Answer: Both B and C ✔

Option A: high current demand

Option B: low voltage demand

Option C: low current demand

Option D: high voltage demand

Correct Answer: high voltage demand ✔

Option A: BJT

Option B: Power dioed

Option C: MOSFET

Option D: None of above

Correct Answer: None of above ✔

Option A: 0 – 0.5 V.

Option B: 0.5 – 1 V.

Option C: 1 – 1.5 V.

Option D: 1.5 – 2 V.

Correct Answer: C. 1 – 1.5 V ✔

Option A: IGBTs

Option B: COOLMOS

Option C: TRIAC

Option D: SITS

Correct Answer: TRIAC ✔

Option A: Reverse recovery time ( trr ) > gate recovery time (tgr)

Option B: Device turn OFF time ( tq ) > reverse recover time (trr)

Option C: Circuit turn OFF time > device turn OFF time ( tq )

Option D: All of these

Correct Answer: All of these ✔

Option A: SIT

Option B: BJT

Option C: TRIAC

Option D: IGBT

Correct Answer: SIT ✔

Option A: 3 – 10 µs

Option B: 3 – 50 µs

Option C: 3 – 100 µs

Option D: 3 – 500 µs

Correct Answer: C. 3 – 100 µs ✔

Option A: B.JTs

Option B: MOSFETs

Option C: IGBTs

Option D: All of above

Correct Answer: All of above ✔

Option A: charge carriers of J2 junction recombined

Option B: charge carriers of J2 junction is swept out

Option C: charge carrier of J1 junction removed

Option D: charge carriers of J3 junction is removed

Correct Answer: charge carriers of J2 junction recombined ✔

Option A: charge carrier of junction J2 recombined

Option B: charge carrier of junction J1 is swept out

Option C: charge carrier of junction J3 is swept out

Option D: both B and C

Correct Answer: both B and C ✔

Option A: SIT is a high power, high frequency device

Option B: SIT is a high power, low frequency device

Option C: SIT is a high power, high voltage device

Option D: SIT is a low power, high frequency device

Correct Answer: SIT is a high power, high frequency device ✔

Option A: Delay time

Option B: Spread time

Option C: Rise time

Option D: Same for every case

Correct Answer: Spread time ✔

Option A: Positive gate signal

Option B: Positive drain signal

Option C: Positive source signal

Option D: None of these

Correct Answer: Positive gate signal ✔

Option A: Filled controlled diode

Option B: Filled controlled rectifier

Option C: Silicon controlled rectifier

Option D: None of these

Correct Answer: Filled controlled diode ✔

Option A: 10 – 20 µs

Option B: 40 – 60 µs

Option C: 1 – 4 µs

Option D: 90 – 100 µs

Correct Answer: C. 1 – 4 µs ✔

Option A: 130 μs

Option B: 135 μs

Option C: 140 μs

Option D: 145 μs

Correct Answer: 135 μs ✔

Option A: delay time

Option B: rise time

Option C: spread time

Option D: all

Correct Answer: rise time ✔

Option A: anode voltage drops from 10 % of its initial value to zero

Option B: anode current rises from 90 % to its final value

Option C: both (A) and (B)

Option D: anode current rises from 10 % to 90 % of its final value

Correct Answer: anode current rises from 90 % to its final value ✔

Option A: Turn on

Option B: Not turn on

Option C: Turn on if inductance is removed

Option D: Turn on if pulse frequency us increased to two times

Correct Answer: Turn on ✔

Option A: Collector, emitter and gate

Option B: Drain, source and gate

Option C: Drain, source and base

Option D: Collector, emitter and base

Correct Answer: Drain, source and gate ✔

Option A: gate current rises from 90 % to 100 % of it final value

Option B: anode voltage drops from 90 % to 10 % of its initial value

Option C: anode current rises 10 % to 90 % of its final value

Option D: both B and C

Correct Answer: both B and C ✔

Option A: IGBT

Option B: FCT

Option C: MCT

Option D: GTO

Correct Answer: IGBT ✔

Option A: gate current increases from 90 % to 100 % of its final value

Option B: anode current reaches 10 % from forward leakage current

Option C: anode voltage drops from 100 % to 90 % of its actual value

Option D: all of these

Correct Answer: all of these ✔

Option A: BJT

Option B: Power MOSFET

Option C: Schottky diode

Option D: Microwave transistor

Correct Answer: Power MOSFET ✔

Option A: in series

Option B: in parallel

Option C: either series or parallel

Option D: anti parallel

Correct Answer: in parallel ✔

Option A: To minimize the loss

Option B: To minimize the charging current

Option C: To minimize the discharging current

Option D: All of these

Correct Answer: To minimize the discharging current ✔

Option A: Unwanted turn ON

Option B: Breakdown of J2 junction

Option C: Both A and B

Option D: Anyone of these

Correct Answer: Both A and B ✔

Option A: Kq/T

Option B: KT/q

Option C: qT/K

Option D: (K2/q)(T + 1/T – 1)

Correct Answer: KT/q ✔

Option A: Breakdown of junction

Option B: Local hot spot

Option C: Insulation failure

Option D: None of these

Correct Answer: Local hot spot ✔

Option A: BJTs and SITs

Option B: BJTs and MOSFETs

Option C: SITs and MOSFETs

Option D: None of these

Correct Answer: BJTs and MOSFETs ✔

Option A: Snubber circuit

Option B: Fuse

Option C: Equalizing circuit

Option D: Circuit breaker

Correct Answer: Snubber circuit ✔

Option A: 1 KVA

Option B: 2 KVA

Option C: 500 VA

Option D: 100 KVA

Correct Answer: 2 KVA ✔

Option A: Fuse.

Option B: Snubber circuit

Option C: Inductor

Option D: Voltage clamping device

Correct Answer: Inductor ✔

Option A: TRIACs

Option B: Semi conductor diodes

Option C: MOSFETs

Option D: Thyristor

Correct Answer: Thyristor ✔

Option A: high thermal conductivity

Option B: large surface area

Option C: high melting point

Option D: All of these

Correct Answer: All of these ✔

Option A: AC switch

Option B: DC switch

Option C: Both a and B

Option D: Square wave switch

Correct Answer: DC switch ✔

A. Iron
B. Aluminium
C. Carbon
D Silver

Correct Answer: Aluminium ✔

Option A: Use of snubber circuit.

Option B: Using heat sink.

Option C: Using CB and fuse.

Option D: Using equalizing circuit

Correct Answer: Using heat sink. ✔

Option A: Controlled transistor

Option B: Controlled switch

Option C: Amplifier with higher gain

Option D: Amplifier with large current gain

Correct Answer: Controlled switch ✔

Option A: lower power circuit.

Option B: high power circuit.

Option C: magnetic circuit.

Option D: may be low power or high power circuit

Correct Answer: lower power circuit. ✔

Option A: gate signal is always present

Option B: gate signal must be removed

Option C: gate signal should present but can be removed

Option D: none of the above.

Correct Answer: gate signal must be removed ✔

Option A: < latching current but greater than holding current and gate signal is 0.

Option B: less than holding current.

Option C: < latching current but greater than holding current and gate signal is present.

Option D: both (A) and (B).

Correct Answer: both (A) and (B). ✔

Option A: 600 V/µs

Option B: 800 V/µs

Option C: 1200 V/µs

Option D: 1000 V/µs

Correct Answer: 800 V/µs ✔

Option A: High power phase control

Option B: High power current control

Option C: Low power current control

Option D: Low power phase control

Correct Answer: High power phase control ✔

Option A: Vc1 > Vc2 > Vc3 when Ig1 > Ig2 > Ig3.

Option B: Vc1 > Vc2 > Vc3 when Ig1 < Ig2 < Ig3.

Option C: Vc1 = Vc2 = Vc3 any value of Ig.

Option D: Vc1 > Vc2 > Vc3 when Ig1 ≥ Ig2 &Atil

Correct Answer: Vc1 > Vc2 > Vc3 when Ig1 < Ig2 < Ig3. ✔

Option A: SIT

Option B: SITH

Option C: GTO

Option D: SCR

Correct Answer: GTO ✔

Option A: Forward voltage triggering

Option B: Gate triggering

Option C: dV / dt triggering

Option D: Thermal triggering

Correct Answer: Gate triggering ✔

Option A: forward blocking mode

Option B: reverse blocking mode

Option C: both forward and reverse blocking mode

Option D: forward conduction mode

Correct Answer: reverse blocking mode ✔

Option A: Recovery is only 5 µs

Option B: Recovery is only 50 µs

Option C: Doping is carried out

Option D: None of these

Correct Answer: Doping is carried out ✔

Option A: CB

Option B: Snubber circuit

Option C: Voltage clamping device

Option D: Fast acting current limiting device (FACL fuse)

Correct Answer: Fast acting current limiting device (FACL fuse) ✔

Option A: High di/dt

Option B: High dv/dt

Option C: Low di/dt

Option D: Low dv/dt

Correct Answer: High di/dt ✔

Option A: of long period

Option B: of short duration

Option C: both (A) and (B)

Option D: neither (A) nor (B)

Correct Answer: of long period ✔

Option A: 20 A

Option B: 200 A

Option C: 600 A

Option D: 400 A

Correct Answer: 200 A ✔

Option A: CB and fuse.

Option B: Heat sink.

Option C: Snubber circuit.

Option D: Voltage clamping device.

Correct Answer: CB and fuse. ✔

Option A: high value.

Option B: low value.

Option C: zero value.

Option D: moderate value.

Correct Answer: high value. ✔

Option A: UJT

Option B: Diac

Option C: Triac

Option D: SCR

Correct Answer: Triac ✔