question_answer

A bar magnet M is dropped so that it falls vertically through the coil C. Obtain the graph for voltage produced across the coil versus time.

(i) Explain which quantity is depicted by the area of graph.

(ii) Why is the negative peak longer than the positive peak?

Answer:

According to the questions, The above graph shows the variation of voltage produced across the coil versus time. When the magnet is coming near the coil, there is a change in flux linkage in the coil and hence an emf is induced in the coil. When the magnet is fully inside the coil, there is no change in magnetic flux, so induced emf becomes zero. When the magnet moves out of the coil, again there is a varying magnetic flux, so induced emf increases.

(i) Area of graph gives the magnetic energy stored in the coil.

(ii) When the magnet enters the coil, its acceleration is less than acceleration due to gravity. So, negative peak is longer.