Question

A bar magnet is oscillating in the Earth's magnetic field with a period T. What happens to this period and motion if this mass is quadrupled -

• A. Motion remains S.H. with time period $=T/2$
• B. Motion remains S.H. with time period $=2T$
• C. Motion remains S.H. with time period $=4T$
• D. Motion remains S.H. with time and period remains nearly constant

Answer 1

The correct option is B

Motion remains S.H. with time period $=2T$

Use $T=2\pi \sqrt{\frac{I}{MB}}$
$\because I\infty mass\Rightarrow T^{\prime }=2\pi \sqrt{\frac{4I}{MB}}=2T$