question_answer

A metal rod moves at a constant velocity in a direction perpendicular to its length. A constant uniform magnetic field exists in space in a direction perpendicular to the rod as well as its velocity. Select the correct statement(s) from the following                                                                          [IIT JEE 1998]

A)            The entire rod is at the same electric potential

B)            There is an electric field in the rod

C)            The electric potential is highest at the centre of the rod and decreases towards its ends

D)            The electric potential is lowest at the centre of the rod and increases towards its ends

Correct Answer: B

Solution :

           A motional emf \[e=Bvl\]is induced in the rod, or we can say, a potential difference is induced between the two ends of the rod AB, with P at higher potential and Q at lower potential. Due to this potential difference, there is an electric field in the rod.