Ques. 1AIPMT 2002
Two bar magnets having same geometry with magnetic moments M and 2M, are firstly placed in such a way that their similar poles are same side then its time period of oscillation is T1. Now the polarity of one of the magnets is reversed then time period of oscillation is T2, then
- T1 < T2
- T1 = T2
- T1 > T2
- T2 =
Answer
(1) T1 < T2
Solution
Time period of a magnet system in field B: T = 2 IMB
Same geometry total moment of inertia = 2I in both cases.
Similar poles on the same side: M1 = M + 2M = 3M
One magnet reversed: M2 = 2M - M = M
T1T2 = M2M1 = 1 3
T1 < T2
Answer: (1)