Obtain an expression for the mutual inductance between a long straight wire and a square of side a as shown in the figure .

Question

$(a) M = \frac{\mu_o a}{2 \pi} log_e \begin{bmatrix} \frac{a}{b} \end{bmatrix}$
$(b) M = \frac{\mu_o a}{2 \pi} log_e \begin{bmatrix} \frac{a}{b} - 1 \end{bmatrix}$
$(c) M = \frac{\mu_o a}{2 \pi} log_e \begin{bmatrix} \frac{b}{a} \end{bmatrix}$
$(d) M = \frac{\mu_o a}{2 \pi} log_e \begin{bmatrix} \frac{a}{b} + 1 \end{bmatrix}$