A planar coil having 12 turns carries 15 A current. The coil is oriented with respect to the uniform magnetic field `B= 0.2hati T` such that its directed area is `A=0.04 hatim^(2).` the potential energy of the coil in the given orientation is

Options

A. 0
B. `+0.72 J`
C. `+1.44J`
D. `-1.44 J`

Answer

C

Explanation

`M= NlA = 12 xx 15 xx 0.04 = 7.2 Am^(2)`
`U= - mB cos theta= - 7.2 xx 0.2 xx cos 180^(@)= 1.44J`