40) A rod of length is l is rotating about an axis at P distance  l from one end as shown in figure. if angular speed of rod is $\omega$ and magnetic field is B₀ out of the page, find emf developed between two points of rod./
$$\begin{gathered} \left(1\right) \frac{1}{2}B\omega l^2 \\ \left(2\right) B{\omega }^2 \\ \left(3\right) \frac{3}{2}B\omega l^2 \\ \left(4\right) Zero \end{gathered}$$