• # question_answer A wire at bent to form a semi-circle of radius. The wire rotates about its one and with angular velocity $\omega$ axis of rotation being perpendicular to plane of the semicircle. In the space, uniform magnetic field of induction B exists along the axis of rotation as shown. The correct statement is: A)  Potential difference between P and Q is equal to $2B\omega {{a}^{2}}$B)  Potential difference between P and Q is equal to $2{{\pi }^{2}}B\omega {{a}^{2}}$C)  P, is at higher potential than QD)  Potential difference between P and Q is zero

As,   emf  $\varepsilon =V\,BL$ $=\frac{1}{2}B{{l}^{2}}\omega =\frac{1}{2}B{{(2a)}^{2}}\omega =2B\omega {{a}^{2}}$ ($\therefore$$L=L/2$ and $V=\omega r=\omega l/2$)