• # question_answer A thin uniform ring of radius $R$ carrying uniform charge $Q$ and mass $M$ rotates about its axis with angular velocity $\omega$. The ratio of its magnetic moment and angular momentum is: A) $\frac{Q}{M}$ B) $\frac{M}{Q}$ C) $\frac{Q}{2M}$            D) $\frac{M}{2Q}$

 $M=iA=\frac{Q}{T}A=\frac{Q\omega }{2\pi }\times \pi {{R}^{2}}=\frac{Q\omega {{R}^{2}}}{2}$ $L=I\omega =M{{R}^{2}}\omega$ $\therefore$      $\frac{M}{L}=\frac{Q\omega {{R}^{2}}/2}{M{{R}^{2}}\omega }=\frac{Q}{2M}.$