A 20 cm long metallic rod is rotated with 210 rpm about an axis normal to the rod passing through its one end. The other end of the rod is in contact…

A $\displaystyle 20$ cm long metallic rod is rotated with $\displaystyle 210$ rpm about an axis normal to the rod passing through its one end. The other end of the rod is in contact with a circular metallic ring. A constant and uniform magnetic field 0.2T parallel to the axis exists everywhere. The emf developed between the centre and the ring is $\displaystyle \_\_\_\_$ mV.Take $\displaystyle \pi=\frac{22}{7}$