1. The value of the flux involved in the emf equation for a transformer is:
a) Instantaneous
b) Maximum
c) Average
d) rms
2. In a transformer operating at constant voltage if the input frequency increases, the core loss:
a) Increases
b) Decreases
c) Remain constant
d) Increases as square of the frequency
3. If the dc voltage is applied instead of ac voltage to the primary side of a transformer:
a) Secondary side will burn
b) Primary side will burn
c) Secondary voltage will be equal to primary voltage
d) No secondary voltage is induced
4. The flux created by the current flowing through the primary winding induces emf in:
a) Primary winding only
b) Secondary winding only
c) both primary and secondary winding
d) None of the above
5. The emf induced in the primary
a) is in phase with the flux
b) lags behind the flux by 90
c) leads the flux by 90
d) it is in phase opposition to that of the flux
6. Total emf induced in the primary winding is due to:
a) mutual flux only
b) leakage flux only
c) both mutual flux and leakage flux
d) mutual flux minus leakage flux
7. The power factor of the transformer on no load is poor due to
a) Magnetising reactance of the transformer
b) Open-circuited secondary
c) Low primary winding resistance
d) Low no load current
8. The no load current of the transformer lags behind the applied voltage by:
a) 90o
b) 0
c) 75o
d) 135o
a) Instantaneous
b) Maximum
c) Average
d) rms
2. In a transformer operating at constant voltage if the input frequency increases, the core loss:
a) Increases
b) Decreases
c) Remain constant
d) Increases as square of the frequency
3. If the dc voltage is applied instead of ac voltage to the primary side of a transformer:
a) Secondary side will burn
b) Primary side will burn
c) Secondary voltage will be equal to primary voltage
d) No secondary voltage is induced
4. The flux created by the current flowing through the primary winding induces emf in:
a) Primary winding only
b) Secondary winding only
c) both primary and secondary winding
d) None of the above
5. The emf induced in the primary
a) is in phase with the flux
b) lags behind the flux by 90
c) leads the flux by 90
d) it is in phase opposition to that of the flux
6. Total emf induced in the primary winding is due to:
a) mutual flux only
b) leakage flux only
c) both mutual flux and leakage flux
d) mutual flux minus leakage flux
7. The power factor of the transformer on no load is poor due to
a) Magnetising reactance of the transformer
b) Open-circuited secondary
c) Low primary winding resistance
d) Low no load current
8. The no load current of the transformer lags behind the applied voltage by:
a) 90o
b) 0
c) 75o
d) 135o
