Consider a hypothetic spherical body.The body is cut into two parts about the diameter. One of hemispherical portion has mass distribution m while the other portion has identical charge distribution q. The body is rotated about the axis with constant speed $\omega$. Then, the ratio of magnetic moment to angular momentum is

A non-conducting non-magnetic rod having circular cross section of radius R is suspended from a rigid support as shown in the figure. A light and small coil of 300 turns is wrapped tightly at the left end of the rod where uniform magnetic field B exists in vertically downward direction.Air of density $\rho$ hits the half of the right part of the rod with velocity V as shown in the figure. What should be current in clockwise direction (as seen from O) in the coil so that rod remains horizontal? Give answer in m A. Given

$\frac{2}{Lv}\sqrt{\frac{\pi RB}{\rho }}=\frac{1}{\sqrt{5}}{ \mathrm{A}}^{-1/2}$