Q. The time period of a freely suspended bar magnet in a field is 2 s. It is cut into two equal parts along its axis, then the time period is
A) 4 s
B) 0.5 s
C) 2 s
D) 0.25 s
Explanation
(c) Time period, $T = 2\pi\sqrt{\frac{I}{MB}}$
$\ \ \ \ \ \ \ \ \ \ T = 2s,\ \ I^{'} = \frac{I}{2},\ \ M^{'} = \frac{M}{2}$
$\therefore\ \ \ \ \ T^{'} = T$
$\Longrightarrow \ \ T^{'} = 2s$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.