Given, magnetic moment, M=6×10−2Am2;moment of inertia, I=12×10−6kgm2; magnetic field, B=2×10−2T; number of oscillations = 20. Now, time period of one oscillation, t=2π√
l
B×M
t=2π√
12×10−6
2×10−2×6×10−2
=2π×10−1
Therefore, time taken by dipole to complete 20 oscillations is