In a uniform magnetic field of induction B, a wire in the form of semicircle of radius r rotates about the diameter of the circle with angular frequency ω. If the total resistance of the circuit is R, the mean power generated per period of rotation is:
1
\( \frac{B \pi r^2 \omega}{2 R}\)
2
\( \frac{\left(B \pi r^2 \omega\right)^2}{8 R}\)
3
\( \frac{(B \pi r \omega)^2}{2 R}\)
4
\( \frac{\left(B \pi r \omega^2\right)^2}{8 R} \)