Physics

Problem

A square loop of side

2a

, and carrying current

I

, is kept in

XZ

plane with its centre at origin. A long wire carrying the same current

I

is placed parallel to the

z

-axis and passing through the point

(0, b, 0)

(b \gg a)

. The magnitude of the torque on the loop about

z

-axis is given by : a.

\frac{\mu_0 I^2 a^2}{2\pi b}

\frac{\mu_0 I^2 a^3}{2\pi b^2}

\frac{2\mu_0 I^2 a^2}{\pi b}

\frac{2\mu_0 I^2 a^3}{\pi b^2}