Question:
A short magnet makes 40 oscillations per minute when used in an oscillation magnetometer at a place where the earth's horizontal magnetic field is $25 \mu \mathrm{T}$. Another short magnet of magnetic moment $1.6 \mathrm{~A}-\mathrm{m}^{2}$ is placed $20 \mathrm{~cm}$ east of the oscillating magnet. Find the new frequency of oscillation if the magnet has its north pole
(a) towards north and
(b) towards south.
Solution:
