Question

Consider the situation shown in the figure. The wire $\text{AB}$ is sliding on the rails with a constant velocity. If the wire is replaced by a semicircular wire, then

• A. Emf induced in the circuit will increase.
• B. Emf induced in the circuit will remain the same.
• C. The direction of induced current will reverse.
• D. The direction of induced current will remain the same.
  

Answer 1

Answer: (B), (D)

The direction of induced current will remain the same.


The emf induced in the wire having effective length $l$ placed in a uniform magnetic field $B$ moving with velocity $v$ is given by,

$E=Bvl$

When the straight wire $\text{AB}$, is replaced by a semicircular wire, the effective length of the semicircular wire will remain the same as the effective length of the straight wire. Therefore, the magnitude of induced emf will be equal.

Since, both the wires are moving in the same direction, therefore, the direction of induced emf and induced current will be same for both cases.

Hence, $\left(\text{B}\right)$ and $\left(\text{D}\right)$ are the correct answers.