A rectangular conducting loop consists of two wires on two opposite sides of length l joined together by rod of length d. The wires are each of the same material but with cross - section differing by a factor of 2. The thicker wire has a resistance R and the rods of low resistance , Which in turn are connected to a constant voltage source $V_0$ the loop is placed in uniform magnetic field B at 45 to its plane . Find the $T$ the torque exerted by the magnetic field on the loop about an axis through the centers of rods.

Question

$\begin{array}{1 1} \large\frac{V_0ld}{4 \sqrt 2 R} \\ \large\frac{V_0lB}{4 \sqrt 2 R} \\ \large\frac{V_0lAB}{ \sqrt 2 R} \\ \large\frac{V_0l AB}{4 \sqrt 2 R} \end{array} $