Chapter 25, Problem 67A

To determine

To Explain:The case when the bulb will be lighted.

Explanation of Solution

Introduction:

The AC current flows through the primary coil and this induces some voltage in the secondary coil. As the load on the secondary coil increases it draws more current from the primary coil. On removal of secondary load, the current in the primary is reduced to the small exciting current.

The bulb will light because there is current present in the secondary circuit. This will take place when the change in the primary current occurs. Thus, the bulb will light when the switch is closed or when the switch is opened. But the bulb will glow only for a moment.