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

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

Answer 1

Answer: (B)

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

$\text{Use the formula:}T=2\pi \sqrt{\frac{I}{MB}}$

$\text{But:}I\propto m$

$T^{{}^{\prime }}=2\pi \sqrt{\frac{4I}{MB}}$

$\Rightarrow \frac{T^{{}^{\prime }}}{T}=2$

$T^{{}^{\prime }}=2T$