Two bar magnets are placed in vibration magnetometer and allowed to vibrate. They make `20` oscillations per minute when their similar pole are on the same side, while they make `15` osicillations per minute when their opposite poles lie on the same side. The ratio of their magnetic moments is

Options

A. `9:5`
B. `25:7`
C. `16:9`
D. `5:4`

Answer

B

Explanation

`M_(1)/M_(2)=(n_(1)^(2)+n_(2)^(2))/(n_(1)^(2)-n_(2)^(2))`