A 250-turns rectangular coil of length 2.1 cm and width 1.25 cm carries a current of `85 muA` and subjected to magnetic field of strength `0.85 T`. Work done for rotating the coil by `180^(@)` against the torque is

Options

A. `9.1 mu J`
B. `4.55 mu J`
C. `2.3 mu J`
D. `1.15 mu J`

Answer

A

Explanation

Work done = 2MB
`=2 xx 250 xx 82 xx 10^(-6) xx 2.1 xx 1.25 xx 10^(-4) xx 0.85`
`= 9.14 xx 10^(-6)J`