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.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 $= \frac { T } { 2 }$

Answer 1

Answer: (A)

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

Answer 2

As $T \propto \sqrt { I }$; where I = moment of inertia

$= \frac { \mathrm { w } L ^ { 2 } } { 12 } \Rightarrow T \propto \sqrt { \mathrm { w } }$ (w = Mass of magnet. If $T ^ { \prime } = 2 T$