Period of oscillation =T Time-period of magnet executing oscillation T=2π√
1
MB
where, I=Ml of magnet about an axis passing through its centre and perpendicular to plane of the magnet M= magnetic moment B= magnetic field Whenthe brass piece is placed, the new time period, T′=2π√
1
MB
So, the time-period remains the same T=T′ Frequency. f′=