Saved Bookmarks
| 1. |
A bar magnet M is dropped so that it falls vertically throughthe coil C [Fig. 6.29). The graph obtained for voltage produced across the coil vs time is shown in Fig. 6.30. (a) Explain the shape of the graph. (b) Why is the negative peak longer than the positive peak? |
|
Answer» Solution :As the mynet APPROACHES the coil C, magnetic flux linked with coil increases and an emf is induced in it which opposes the in- crease in flux. When magnet is fully inside the coil, magnetic flux linked with coil becomes constant and, HENCE, induced emf falls to zero. As the magnet falls below the coil, magnetic flux of the coil decreases. As a result, an induced emf is SET up which opposes the decrease in flux i.e., which tends to increase the magnetic flux. Thus, induced emf now is in a direction OPPOSITE to that EARLIER. As velocity of magnet has increased during its fall, the negative peak of emf is longer than the positive peak. When the magnet has fallen through large distance, magnetic flux of coil becomes constant and induced emf vanishes. |
|