• # question_answer A wheel having metal spokes 1 m long between its axle and rim is rotating in a magnetic field of flux density $5\times {{1}^{-5}}T$normal to the plane of the wheel. An emf of 22/7 mV is produced between the rim and the axle of the wheel. The rate of rotation of the wheel in radians per second is: A) 10                   B) 20                   C)      30                 D)      40

Induced $em\,V=Blv$or $v=\frac{V}{Bl}=\frac{\frac{22}{7}\times {{10}^{-3}}}{5\times {{10}^{-5}}\times 1}=20\,T$ or $v=w=20\,rad/\sec .$ Hence, the correction option is (b).