Magnetism Question 130
Question: A bar magnet is oscillating in the Earth’s magnetic field with a period T. What happens to its period and motion if its mass is quadrupled
[CBSE PMT 2003]
Options:
A) Motion remains S.H.M. with time period = 2T
B) Motion remains S.H.M. with time period = 4T
C) Motion remains S.H.M. and period remains nearly constant
D) Motion remains S.H.M. with time period $ =\frac{T}{2} $
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Answer:
Correct Answer: A
Solution:
As $ T\propto \sqrt{I} $ ; where I = moment of inertia $ =\frac{\text{w}L^{2}}{12}\Rightarrow T\propto \sqrt{\text{w}} $ (w = Mass of magnet. If $ \text{w}\to $ quadrupled, then $ T\to $ doubled i.e. $ {{T}^{’}}=2T $
BETA
