A uniform conducting wire of length $12a$ and resistance R is wound up as a current carrying coil in the shape of an equilateral triangle of side a. the coil is connected to a voltage source of $V_0$ Find the magnetic of the coil .

Question

$\begin{array}{1 1} \frac{\sqrt 3}{4} Ia^2 \\ \frac{\sqrt 3}{4} Ia \\ \sqrt 3 Ia^2 \\ \sqrt 3 Ia \end{array}$