A bar magnet is suspended in a region where it is acted upon by two magnetic fields inclined at an angle of `60^@` to each other. One of the fields has a magnitude of `1*2xx10^-2T`. The magnet attains stable equilibrium at an angle of `15^@` with this field. Calculate the magnitude of other field. Ignore earth's field.

Answer

`4*4xx10^-3T`

Explanation

Here, `B_1=1*2xx10^-2T`, `theta_1=15^@`,
`theta_2=60^@-15^@=45^@`, `B_2=?`
In equilibrium, `tau_1=tau_2`
`MB_1sintheta_1=MB_2sintheta_2`
`B_2=(B_1sintheta_1)/(sintheta_2)=(1*2xx10^-2sin15^@)/(sin45^@)`
`=4*4xx10^-3T`