Monday, November 28, 2016

Multiple Choice Questions with Answers on Thyristors (SCR)

Multiple Choice Questions Answers on Thyristors (SCR)

1. An SCR is a ...... triggered device
(1) Voltage
(2) Current
(3) Voltage as well as current
(4) None of the above


2. In an SCR circuit, the supply voltage is generally ......... that of breakover voltage
(1) Equal to
(2) Less than
(3) Greater than
(4) None of the above


3. When an SCR is turned on, the voltage across it is about ..........
(1) zero
(2) 10 V
(3) 0.1 V
(4) 1V


4. An SCR is turned off when
(1) Anode current is reduced to zero
(2) Gate voltage is reduced to zero
(3) Gate is reverse biased
(4) None of the above


5. In an SCR circuit, the angle of conduction can be changed by
(1) Changing anode voltage
(2) Changing gate voltage
(3) Reverse biasing the gate
(4) None of the above


6. If firing angle is increased, then the output of an SCR
(1) Remains the same
(2) Is increased
(3) Is decreased
(4) None of the above


7. If gate current is increased, then anode-cathode voltage at which SCR turns ON
(1) is decreased
(2) is increased
(3) remains the same
(4) none of the above


8. An SCR has ........... PN junctions.
(1) Two
(2) Three
(3) Four
(4) None of the above


9. An SCR has ........ semiconductor layers.
(1) Two
(2) Three
(3) Four
(4) None of the above


10. In AC supply,  an SCR can exercise control over
(1) Positive half-cycles only
(2) Negative half-cycles only
(3) Both positive and negative half-cycles
(4) Positive or negative half-cycles


11. AC power in a load can be controlled  by connecting
(1) Two SCRs in series
(2) Two SCRs in parallel
(3) Two SCRs in parallel opposition
(4) None of the above


12. When SCR starts conducting, which loses all control?
(1) Cathode
(2) Gate
(3) Anode
(4) None of the above


2:10 AM