The length of the conductor in the diagram shown in Fig. 30.5 is l= 20 cm, its speed is v=1 m/s and the resistance of the bulb is R =1 ohm. A magnetic field with induction B=0.5 T is set up perpendicular to the plane of the diagram. What force should be applied to the conductor to make it move at the speed specified?

Answer

0.01N

Explanation

The force applied to a conductor moving at a constant speed is equal in magnitude to the magnetic force. But the current is `l=(epsi)/R=(Blv)/R` hence `F-iBl=B^2l^2vlR`