JEE Physics 2026 Question with Solution

Given: Three identical coils $C_1$, $C_2$ and $C_3$ share a common axis, with $C_2$ midway between the other two. $C_1$ carries current $I$ in anti-clockwise direction and $C_3$ carries current $I$ in clockwise direction.

Find: The condition for which the induced current in $C_2$ is in clockwise direction.

Step 1: Determine magnetic field directions.

• $C_1$ carries current in anti-clockwise direction, so its magnetic field at $C_2$ is out of the plane.
• $C_3$ carries current in clockwise direction, so its magnetic field at $C_2$ is also out of the plane.

Thus, both coils produce magnetic flux in the same direction through $C_2$.

Step 2: Apply Lenz's law. According to Lenz’s law, the induced current opposes the change in magnetic flux.

Step 3: Analyze option (C).

• $C_1$ moves towards $C_2$: magnetic flux through $C_2$ increases.
• $C_3$ moves away from $C_2$: magnetic flux through $C_2$ decreases.

Net effect: decrease in outward magnetic flux through $C_2$.

Step 4: Direction of induced current. To oppose the decrease in outward flux, the induced current in $C_2$ must produce outward magnetic field. This corresponds to a clockwise induced current.

Therefore, the correct option is C.

Given: The magnetic flux through $C_2$ is due to both $C_1$ and $C_3$.

Find: When the induced current in $C_2$ becomes clockwise.

The key idea is to first check whether the net outward magnetic flux through $C_2$ increases or decreases.

If the net outward flux decreases, then by Lenz’s law the induced current must try to maintain outward flux.

A clockwise induced current is required in this case according to the provided solution logic.

In option C, one source of outward flux weakens overall, so the net outward flux decreases. Hence the induced current is clockwise.

Therefore, the correct option is C.