Multiple Choice Questions
1 Which of the following is the application of Power Electronics?- (A) Fan Regulator
- (B) Temperature controller
- (C) Cycloconverter
- (D) All the above
2 Which of the following is not triggering device?
- (A) UJT
- (B) SCR
- (C) DIAC
- (D) SBS
3 Long form of SCR is
- (A) Silicon Conversion Rectifier
- (B) Silicon Controlled Rectifier
- (C) Selenium Controlled Rectifier
- (D) None of the above
4 Which of the following is not Power Controlled Rectifier?
- (A) SCR
- (B) TRIAC
- (C) UJT
- (D) LASCR
5 SCR is a…..
- (A) Four Layer Three Terminal Device
- (B) Three Layer Four Terminal Device
- (C) Four Layer Four Terminal Device
- (D) Four Layer Two Terminal Device
6 TRIAC is a
- (A) Unidirectional device
- (B) Bidirectional Device
- (C) Sometime Bidirectional device
- (D) Cannot say
7 Which of the following is not part of VI characteristics of SCR?
- (A) Forward Blocking state
- (B) Forward Conduction state
- (C) Saturation State
- (D) Reverse Blocking State
8 Which of the following holds true for relationship between Holding current and Latching Current?
- (A) Holding Current > Latching current
- (B) Holding Current < Latching current
- (C) Holding Current = Latching current
- (D) Holding Current <= Latching current
9 As value of gate current through SCR increases
- (A) Value of breakover voltage decreases
- (B) Value of breakover voltage increases
- (C) Value of breakover voltage remains unchanged
- (D) None of the above
10 On state voltage drop across SCR is approximately equals to
- (A) 10 volts
- (B) 100 volts
- (C) 0.1 volt
- (D) 1 volt
11 Following symbol represents…
- (A) DIAC
- (B) TRIAC
- (C) SCR
- (D) UJT
12 Which of the following is most widely used turn on methods of SCR?
- (A) Gate Triggering
- (B) Light Triggering
- (C) Forward Voltage Triggering
- (D) dv/dt Triggering
13 Which of the following Thyristor can be turned on by light triggering?
- (A) SCR
- (B) TRIAC
- (C) DIAC
- (D) LASCR
14 Two transistor analogy of SCR can be achieved by using
- (A) Any two-transistor choice
- (B) Two PNP transistor
- (C) One PNP and One NPN transistor
- (D) One FET and One MOSFET transistor
15 For Protecting SCR from over voltage which of the following protection technique is used
- (A) Snubber Circuit
- (B) Inductor is connected in series
- (C) Fuse is connected in series
- (D) Heat sink
16 Commutation is process of
- (A) Turning On SCR
- (B) Turning Off SCR
- (C) Checking SCR
- (D) Converting SCR into TRIAC
17 Which of the following is not Forced Commutation?
- (A) Class A commutation
- (B) Class C commutation
- (C) Class E commutation
- (D) Class F commutation
18 Class C commutation is also called as
- (A) Auxiliary Commutation
- (B) Resonant Commutation
- (C) Self-Commutation
- (D) Complimentary Commutation
19 Following diagram represents which type of commutation
- (A) Auxiliary Commutation
- (B) Resonant Commutation
- (C) Self-Commutation
- (D) Complimentary commutation
20 Following symbol represents which triggering device
- (A) UJT
- (B) PUT
- (C) DIAC
- (D) SBS
21 In Forward blocking state, Junctions
- (A) J1 – Forward Bias, J2-Forward Bias, J3- Forward Bias
- (B) J1 – Forward Bias, J2-Forward Bias, J3- Reverse Bias
- (C) J1 – Reverse Bias, J2-Forward Bias, J3- Reverse Bias
- (D) None of the above
22 Role of protection circuit is
- (A) Protect load from excess current and voltages
- (B) Protect Source from excess current and voltages
- (C) Protect SCR (Thyristor) from excess current and voltages
- (D) None of the above
23 UJT exhibits …………………… in its characteristics
- (A) Positive Resistance Region
- (B) Negative Resistance Regio
- (C) Non Ohmic Region
- (D) Conductive Region
24 Long form of PUT is
- (A) Programmable Uni Junction Transistor
- (B) Programmable Unique Junction Thyristor
- (C) Pointed Unit Transitory
- (D) None of the above
25 Pulse duration in UJT relaxation oscillator is controlled by using
- (A) R and C combination
- (B) Restore Only
- (C) Capacitor only
- (D) By UJT