A non-conducting hollow sphere of mass m and radius R having total charge 'q' is rotating with constant angular velocity
′ω′ about a vertical axis as shown in the figure. The sphere is then gently placed on the horizontal surface having a magnetic field applied in the horizontal direction as shown. If there is sufficient friction to prevent any slipping, then the friction force acting on the sphere at
t=0 is
qωRBn. Find the value of n.
![769174_6192bcada3634f0fa6799d919edbb725.png](https://search-static.byjusweb.com/question-images/toppr_invalid/questions/769174_6192bcada3634f0fa6799d919edbb725.png)