No-load current in a transformer

The correct answer is: C. lags behind the voltage by about 15°

No-load current is the current that flows in a transformer when there is no load connected to the secondary winding. It is caused by the magnetization of the core by the primary winding current. The no-load current is small compared to the load current, and it lags the voltage by about 15°.

Option A is incorrect because the no-load current lags the voltage, not leads it.

Option B is incorrect because the no-load current is much smaller than the load current.

Option D is incorrect because the no-load current lags the voltage by about 15°, not 75°.