IBPS PO General Awareness: Electricity and Magnetism questions with solutions

Q1. Large transformers, when used for some time, become very hot and are cooled by circulating oil. The heating of the transformer is due to

1. the heating effect of current alone
2. hysteresis loss alone
3. both the heating effect of current and hysteresis loss
4. intense sunlight at noon

Answer: both the heating effect of current and hysteresis loss

A transformer heats up mainly because of copper loss in the windings and hysteresis loss in the iron core. These losses convert electrical energy into heat, so oil is used to carry away the heat.