Question

A metal rod $\text{AB}$ moves at a constant velocity $V$ in a direction perpendicular to its length. A constant uniform magnetic field $B$ exists in space in a direction perpendicular to the rod as well as its velocity. Select the correct statement(s) from the following.

• A. The electric potential is highest at the centre of the rod and decrease towards its ends
• B. The electric potential is lowest at the centre of the rod and increase towards its ends
• C. The entire rod is at the same electric potential
• D. There is an electric field in the rod

Answer 1

The correct option is D There is an electric field in the rod

When $B,l$ and $V$ are perpendicular to each other, then an emf is induced in the rod known as motional emf which will be,

$E=BlV$

Or, we can say a potential difference is induced between the two ends of the rod $\text{AB}$, with $\text{A}$ at higher potential and $\text{B}$ at lower potential. Due to this potential difference, there is an electric field generate in the rod.

Hence, option $\left(\text{B}\right)$ is the right choice.