Transformers MCQ Questions and Answers for Practice

1. When AC supply is given to the transformer, the flux will depend on

1. current
2. voltage
3. frequency
4. both voltage and frequency

2. In transformer, humming sound occurs due to

1. oil
2. load
3. magnetostriction
4. none of above

3. As compared the transformer with AC machines it is more efficient because

1. it does not have mechanical losses
2. it does not have copper losses
3. core losses negligible
4. none of above

4. The primary and secondary winding of transformer are linked each other by

1. conduction
2. mutual induction
3. not linked at all
4. self induction

5. Which parameter does not change during transformation action in transformer?

1. Voltage
2. Frequency
3. Current
4. None of these

6. Secondary current of a step down transformer is

1. lower than primary current
2. higher than primary current
3. equal to primary current
4. double than primary current

7. The core of transformer must have

1. low reluctance
2. high resistance
3. high reluctance
4. low resistance

8. The working principle of transformer depends upon

1. Ohms Law
2. Lenz Law
3. Flemings left hand rule
4. Faradays law of electromagnetic induction

9. An ideal transformer is one which has

1. no winding resistance
2. no leakage reactance
3. no losses
4. all of above

10. In an ideal transformer the magnetizing current lags behind applied primary voltage by an angle

1. 90 degree
2. 75 degree
3. -90 degree
4. 45 degree

11. In an ideal transformers primary and secondary induced emfs are

1. self induced emfs
2. mutually induced emfs
3. self and mutually induced emfs respectively
4. mutually and self induced emfs respectively

12. The input power under no load condition of transformer consists of

1. core losses in transformer
2. core losses and very small amount of copper loss in primary
3. copper loss in transformers
4. significant copper loss along with negligible core losses

13. In a transformer the coils of primary and secondary are placed concentrically to achieve

1. reduced leakage flux between primary and secondary winding
2. reduced copper losses in the winding
3. reduced insulation cost of the windings
4. reduced voltage per turn in the winding

14. Iron loss in transformer can be determined by

1. short circuit test
2. open circuit test
3. both short circuit and open circuit tests
4. none of the above

15. No load losses in a transformer can be minimized by using steel of

1. high silicon content and very thin lamination
2. only high silicon content
3. only very thin lamination
4. low silicon content and very thin lamination