Figure. shows one quarter of a simple circular loop of wire that carries a current of 14 A. Its radius is `a=5 cm.` A uniform magnetic field, `B =300 G,` is directed in the +x direction. Find the torque on the entire loop and the direction in which it will rotate.

Options

A. `2.9xx10^-3Nm`
B. `1.9xx10^-3Nm`
C. `6.2 Nm`
D. `0.5xx10^-3Nm`

Answer

A

Explanation

The normal to the loop, `OP` makes an angle `theta=60^(@)`
with `+X` direction, i.e., along the field direction.
Hence, Torque `tau=NiABsintheta`
`tau=1xx14xxpi(25xx10^(-4))(0.03)xxsin60^(@)`
`=2.9xx10^(-3)N-m`