Question

When a bar magnet falls through a long hollow metal cylinder fixed with its axis vertical, the final acceleration of the magnet is
(a) Equal to zero(b) Less than g
(c) Equal to g(d) Equal to g in to beginning and then more than g

Answer 1

answer : option (a) equal to zero

explanation : answer : option (A)

explanation : if A bar magnet is falling vertically down through the hollow region of metal cylindrical tube, then magnetic flux linked with the metal tube changes and hence, eddy currents are generated in the body of the tube .

according to Lenz's law, eddy currents oppose the falling of magnetic bar due to this bar magnet experiences retarding force. here retarding force depends on velocity of magnet. when velocity of bar magnet increases, retarding force also increases and finally retarding force equals weight of bar magnet. Then, magnet attains constant terminal velocity. e.g., bar magnet ultimately fall with zero acceleration .

hence, When a bar magnet falls through a long hollow metal cylinder fixed with its axis vertical, the final acceleration of the magnet is equal to zero.