The magnetic field in a region is given by $\overrightarrow{\mathrm{B}}-=\mathrm{B}_0\left(\frac{\mathrm{x}}{\mathrm{a}}\right) \hat{\mathrm{k}}$. A square loop of side d is placed with its edges along the x and y axes. The loop is moved with a constant velocity $\overrightarrow{\mathrm{v}}=\mathrm{v}_0 \hat{\mathrm{i}}$. The emf induced in the loop is: