ODBAC is a fixed rectangular conductor of negligible resistance (CO is not connected) and OP is a conductor which rotates clockwise with an angular velocity (Fig 6.12). The entire system is in a uniform magnetic field B whose direction is along the normal to the surface of the rectangular conductor ABDC. The conductor OP is in electric contact with ABDC. The rotating conductor has a resistance of λ per unit length. Find the current in the rotating conductor, as it rotates by 180°.
between time t=0 and t= 
,the rod OP will make contact with slide BD at any time
t:0< t< 
let the length OQ be x
hence the magnetic flux through the area ODQ is
∴ θ 
t
∴ magnitude of EMF generated is e = 
if R is the resistance of the rod in contact, then induced current 
∴ 
