Electronics Engineering MCQs
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The effect of source inductance in a 3 phase fully controlled bridge converter is to
- A. decrease the output voltage
- B. increase the output voltage
- C. decrease the output voltage and increase the output current
- D. increase the output voltage and decrease the output current
- Correct Answer: Option A
The snubber circuit consists of
- A. a capacitor connected in series with thyristor
- B. a capacitor connected in parallel with thyristor
- C. a resistor and capacitor in series connected across thyristor
- D. none of the above
- Correct Answer: Option C
A single phase dual converter consists of
- A. two fully controlled converters connected in parallel
- B. two fully controlled converters connected in antiparallel
- C. two fully controlled semiconverters connected in antiparallel
- D. two fully controlled semiconverters connected in parallel
- Correct Answer: Option B
Assertion (A): A class C chopper can operate in first and second quadrants Reason (R): A class B chopper operates only in second quadrant.
- 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
In a 3 phase bridge inverter with 120° mode of operation the. number of thyristors conducting at one time are
- A. 1
- B. 2
- C. 3
- D. 4
- Correct Answer: Option B
A single phase cycloconverter with centre tapped input transformer requires
- A. 2 thyristors
- B. 4 thyristors
- C. 8 thyristors
- D. either 2 or 4 thyristors
- Correct Answer: Option B
A LASCR has
- A. 4 semiconductor layers and 3 junctions
- B. 3 semiconductor layers and 2 junctions
- C. 2 semiconductor layers and 2 junctions
- D. any of these depending on the rating
- Correct Answer: Option A
In Jone chopper, the commutating element
- A. is a capacitor
- B. is a capacitor and an inductor
- C. is a capacitor and an auto transformer
- D. none of the above
- Correct Answer: Option C
A dc series motor is coupled to a load whose torque is proportional to speed. It is fed by a single phase ac supply through a full converter. When speed is 500 rpm, firing angle is 45°. It is desired to raise the speed. It will be necessary to
- A. decrease the firing angle
- B. increase the firing angle
- C. either decrease or increase the firing angle depending on the required speed
- D. decrease the load torque
- Correct Answer: Option A
When an SCR is reverse biased
- A. two junctions are reverse biased and one junction is forward biased.
- B. all the three junctions are reverse biased.
- C. one junction is reverse biased and two junctions are forward biased.
- D. any of the above depending on the magnitude of reverse bias.
- Correct Answer: Option A