A circular metal plate of radius R is rotating with a uniform angular velocity \[\omega \]with its plane perpendicular to a uniform magnetic field B. Then the emf developed between the centre and the rim of the plate is [UPSEAT 2004]

• A.            \[\pi \omega B{{R}^{2}}\]      
• B.            \[\omega B{{R}^{2}}\]  
• C.            \[\pi \omega B{{R}^{2}}/2\]  
• D.            \[\omega B{{R}^{2}}/2\]