Q4. A copper coil L wound on a soft iron core and a lamp B are connected to a battery E through a tapping key K. When the key is closed, the lamp glows dimly. But when the key is suddenly opened, the lamp flashes for an instant to much greater brightness.Explain why?
BEACAUSE WHEN THE CURRENT IS SUDDENLY CUT OFF THE FLUX LINKED WITH COIL CHANGES INDUCING CURRENT IN THE CIRCUIT.SO CURRENT INCREASES IN TOTAL CIRCUIT HENCE BULB GLOWS BRIGHTER FOR AN INSTANT .