A bar magnet is suspended in a uniform magnetic field in a position such that it experiences maximum torque. The angle through which it must be rotated from this position such that it experiences half of the maximum torque.

Options

A. `60^(@)`
B. `30^(@)`
C. `90^(@)`
D. `45^(@)`

Answer

A

Explanation

`tau oosintheta`
`therefore (sintheta_(2))/(sintheta_(1))=(tau_(2))/(tau_(1))`
`(Sintheta_(2))/(sin90)=(tau_(1))/(2tau_(1))`
`sin0_(2)=(1)/(2)`
` therefore 0_(2)=30^(@)`
`therefore "angle of rotation"=90-30=60^(@)`