As shown in figure a conducting circular loop of radius a placed in a uniform perpendicular magn...

As shown in figure a conducting circular loop of radius a placed in a uniform perpendicular magnetic field \( \mathrm{B} \). A metal rod \( \mathrm{OA} \) is pivoted at centre \( \mathrm{O} \) of the loop. The other end \( A \) of the rod touches the loop. The rod \( \mathrm{OA} \) and the loop are resistanceless but a resistor having resistance \( R \) is connected between \( \mathrm{O} \) and a fixed point \( \mathrm{C} \) on the loop. The rod OA made to rotate anticlockwise at a small but uniform angular speed \( \omega \) by an external force. The current in the resistance \( R \) is
(1) \( \mathrm{I}=\frac{\mathrm{B} \omega \mathrm{a}^{2}}{2 \mathrm{R}} \)
(2) \( \quad I=\frac{B^{2} \omega^{2} a^{2}}{2 R} \)
(3) \( \quad I=\frac{B \omega a^{2}}{R} \)
(4) \( \quad I=\frac{B^{2} \omega^{2} a^{2}}{2 R} \)