A metallic rod of length $‘A’$ is tied to a string of length $2A$ and made to rotate with angular speed $\omega$ on a horizontal table with one end of the string fixed. If there is a vertical magnetic field ‘B’ in the region, the e.m.f. induced across the ends of the rod is :

Question

$\begin{array}{1 1}(1) \large\frac{2Bwl^2}{2} \\(2) \large\frac{3Bwl^2}{2} \\ (3) \large\frac{4Bwl^2}{2} \\ (4)\large\frac{5Bwl^2}{2} \end{array}$