1. Why there is an enamel layer coated over the lamination of the transformer core?
a) To decrease the hum
b) To attain adhesion between the lamination
c) To insulate the laminations against each other
d) To prevent the corrosion of the laminations.
ans. c
2. What is the efficiency of transformer compared with that of electrical motors of the same power?
a) Much smaller
b) Some what smaller
c) About the same
d) Much higher
ans. d
3. According to the name plate of a small transformer, the secondary normal voltage is 220 V. Which of the following statements about it is true?
a) The no-load voltage is more than 220V.
b) 220V is the no-load voltage.
c) At a load which draws the rated current, the voltage becomes less than 220 V
d) The secondary voltage increases with increasing load.
ans. a
4. Upon which factor does the short circuit voltage of a transformer mainly depend. It depends
a) on the ohmic resistance of the primary winding
b) on the ohmic resistance of the secondary winding
c) on the cross-sectional area of their core
d) on the magnitude of the leakage flux
ans. d
5. Which of the following statements about a transformer having a small short circuit voltage is true?
a) The transformation ratio of the transformer is small
b) During the operation the transformer has high iron losses
c) During operation the transformer has high copper losses
d) A high short circuit current flows through the transformer.
ans. d
6. What is the typical use of an auto-transformer?
a) Isolating transformer
b) Toy transformer
c) Control transformer
d) Variable transformer
ans.d
7. In any transformer, the voltage per turn in primary and secondary remains
a) always same
b) always in ratio of K
c) always different
d) sometimes same.
ans. a
8. In any single phase transformer, the primary and secondary induced voltages are
a) 180 degrees out of phase
b) 90 degrees out of phase
c) in phase
d) none of these
ans. c
9. The no load current taken by actual transformer lags the applied voltage by
a) 80 degrees
b) 60 degrees
c) 50 degrees
d) 30 degrees
ans. a
10. The full load copper-loss in a transformer is 400 W. At half load, the copper-loss will be
a) 400 W
b) 200 W
c) 100 W
d) 50 W
ans. c
a) To decrease the hum
b) To attain adhesion between the lamination
c) To insulate the laminations against each other
d) To prevent the corrosion of the laminations.
ans. c
2. What is the efficiency of transformer compared with that of electrical motors of the same power?
a) Much smaller
b) Some what smaller
c) About the same
d) Much higher
ans. d
3. According to the name plate of a small transformer, the secondary normal voltage is 220 V. Which of the following statements about it is true?
a) The no-load voltage is more than 220V.
b) 220V is the no-load voltage.
c) At a load which draws the rated current, the voltage becomes less than 220 V
d) The secondary voltage increases with increasing load.
ans. a
4. Upon which factor does the short circuit voltage of a transformer mainly depend. It depends
a) on the ohmic resistance of the primary winding
b) on the ohmic resistance of the secondary winding
c) on the cross-sectional area of their core
d) on the magnitude of the leakage flux
ans. d
5. Which of the following statements about a transformer having a small short circuit voltage is true?
a) The transformation ratio of the transformer is small
b) During the operation the transformer has high iron losses
c) During operation the transformer has high copper losses
d) A high short circuit current flows through the transformer.
ans. d
6. What is the typical use of an auto-transformer?
a) Isolating transformer
b) Toy transformer
c) Control transformer
d) Variable transformer
ans.d
7. In any transformer, the voltage per turn in primary and secondary remains
a) always same
b) always in ratio of K
c) always different
d) sometimes same.
ans. a
8. In any single phase transformer, the primary and secondary induced voltages are
a) 180 degrees out of phase
b) 90 degrees out of phase
c) in phase
d) none of these
ans. c
9. The no load current taken by actual transformer lags the applied voltage by
a) 80 degrees
b) 60 degrees
c) 50 degrees
d) 30 degrees
ans. a
10. The full load copper-loss in a transformer is 400 W. At half load, the copper-loss will be
a) 400 W
b) 200 W
c) 100 W
d) 50 W
ans. c
