1. A PNPN diode is a ?

negative resistance device

current controlled device

current controlled negative resistance device

voltage controlled device

Answer: current controlled negative resistance device

Explanation:


2. An SCR may be turned OFF by ?

reversing polarity of its anode cathode voltage

interrupting its anode current

low-current dropout

all of the above

Answer: all of the above

Explanation:


3. Value of breakover voltage for the commonly used diacs is about ?

52 V

22 V

78 V

32 V

Answer: 32 V

Explanation:


4. The trigger voltage of a SCR is closest to ?

0.3 V

0.7 V

3 V

A break down voltage

Answer: A break down voltage

Explanation:


5. The most commonly used method for firing an SCR is the ?

voltage triggering process

radiation triggering process

thermal triggering process

gate triggering process

Answer: gate triggering process

Explanation:


6. SCR are connected in parallel to enhance ?

di/dt rating

current handling capability

voltage handling capability

none of the above

Answer: current handling capability

Explanation:


7. An SCR can be operated ?

only on reverse biased condition

only on forward biased condition

both forward and reverse biased conditions

without any biasing

Answer: only on forward biased condition

Explanation:


8. A diac is a ?

Two layer three junction device

three-layer two-junction device

four-layer two-junction device

four-layer three-junction device

Answer: three-layer two-junction device

Explanation:


9. In half wave SCR power control circuit if the firing angle is 30°, then for one complete cycle of operation, the load gets power for ?

40°

150°

360°

60°

Answer: 150°

Explanation:


10. A three-phase full-wave fully controlled bridge uses ?

2 SCRs

3 SCRs

8 SCRs

6 SCRs

Answer: 6 SCRs

Explanation: