A switch S is connected in series with a battery and a long straight wire placed…
PHYSICS · Subjective · AP · Physics 2: Algebra-based · Magnetism and Electromagnetism · Magnetism and Electromagnetism
Problem
A switch S is connected in series with a battery and a long straight wire placed directly below a small compass needle. The switch is kept open for some time, then closed for a few seconds, and finally opened again. The needle shows a sharp deflection at the instants of closing and opening but remains steady in between. Explain the reason for the needle’s behaviour at all three stages.