In the arrangement shown, what is the expression for emf induced in the smaller loop of radius $r?$ The current $I$ varies as $I=3 t+5(R>>r)$

A uniform and constant magnetic field $B$ coming out of the plane of the paper exists in a rectangular region as shown in figure. $A$conducting rod $PQ$ is rotated about its mid-point $O$ with a uniform angular speed $\omega$ in the plane of the paper. The emf $E_{PQ}$ induced between $P$ and $Q$ is best represented by the graph

A conducting ring of radius a falls vertically downward with a velocity $v_0$ in a horizontal magnetic field $B.$ The potential difference between two points $P$ and $Q$ located symmetrically on both sides of the vertical will be