Electronics Engineering MCQs
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A thyristor circuit is feeding an R-L load. The turn on time can be reduced by
- A. decreasing R
- B. decreasing L
- C. increasing L
- D. decreasing R and L together
- Correct Answer: Option B
Which chopper circuit uses saturable reactor?
- A. Auxiliary commutated
- B. Jones chopper
- C. Morgan chopper
- D. Load commutated
- Correct Answer: Option C
In auxiliary commutated chopper, the charging and discharging time of capacitor
- A. are constant
- B. depend on load current
- C. may be constant or may depend on load current
- D. none of the above
- Correct Answer: Option B
When a UJT is used as a relaxation oscillator the current should be
- A. less than Ip
- B. more than Iv
- C. more than Ip but less than Iv
- D. negative
- Correct Answer: Option C
Assertion (A): An ac regulator uses natural commutation Reason (R): An ac regulator can be used for static on load tap changing of transformer.
- A. Both A and R are correct and R is correct explanation of A
- B. Both A and R correct but R is not correct explanation of A
- C. A is correct but R is wrong
- D. A is wrong but R is correct
- Correct Answer: Option B
For an illumination control circuit it is advisable to use a matched TRIAC-DIAC pair.
- A. True
- B. False
- Correct Answer: Option A
In a controlled rectifier a freewheeling diode is necessary if the load is
- A. inductive
- B. resistive
- C. capacitive
- D. any of the above
- Correct Answer: Option A
In the basic series inverter circuit, the source current has
- A. low harmonic content
- B. high harmonic content
- C. low or high harmonic content depending on firing angle
- D. zero harmonic content
- Correct Answer: Option B
A single phase full bridge inverter for R-L loads needs
- A. 4 thyristors
- B. 4 thyristors and 4 diodes
- C. 4 thyristors and 2 diodes
- D. 8 thyristors
- Correct Answer: Option B
In a cycloconverter it is possible to vary
- A. only output frequency
- B. only output voltage
- C. both output voltage and frequency but not simultaneously
- D. both output voltage and output frequency simultaneously
- Correct Answer: Option D