Q. Two bar magnets having same geometry with magnetic moments $M$ and 2 $M$ are firstly placed in such a way that their poles are same side. Time period of oscillations is $T_{1}$. Now the polarity of one of the magnets is reversed, and time period of oscillations is $T_{1}$. Now the polarity of one of the magnets is reversed, and time period of oscillations is $T_{2}$.
A) $T_{1} < T_{2}$
B) $T_{1} = T_{2}$
C) $T_{1} > T_{2}$
D) $T_{2} = \infty$
Explanation
(a) When polarity is reversed, net magnetic moment $2M - M = M$, decreases. Therefore time period of oscillation increases $ie,\ T_{2} > T_{1}\ or\ T_{1} < T_{2}$.
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.