Let magnetic dipole moment of given magnet is M. Then, its oscillation time period is
T=2π√=2s( given
) where,
I= moment of inertia
= and
M= magnetic dipole moment of magnet. When magnet is cut into 3 parts, each part length is
l/3 and mass of each part will be
ω/3 So, moment of inertia of each part will be
I′===×I Also, magnetic dipole moment of each part will be
M′= Now, when these parts are placed one over other with like poles together,
Moment of inertia of combination
=I1=3×I=I Also, dipole moment of combination is
M1=3×=M Hence, time period of oscillation of combination is