A metallic rod of length $‘l’$ is tied to a string of length $2l$ 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: <br>

Question

( A ) $\frac{3 B \omega \ell^2}{2}$
( B ) $\frac{5 B \omega \ell^2}{2}$
( C ) $\frac{4 B \omega \ell^2}{2}$
( D ) $\frac{2 B \omega \ell^2}{2}$