Exams › JEE Advanced › Physics

A horizontal solenoid is connected to a battery through a switch. A copper ring is placed on a frictionless track with its axis along the solenoid's axis. When the switch is closed, the ring will:

1. remain stationary
2. move towards the solenoid
3. move away from the solenoid
4. move towards the solenoid or away from it depending on which terminal of the battery is connected to the left end of the solenoid.

Correct answer: move away from the solenoid

Solution

When the switch closes, current grows in the solenoid and the magnetic flux through the ring rises. By Lenz's law the ring's induced current opposes this increase, making the ring magnetically equivalent to a like pole facing the solenoid, so it is repelled and moves away. This is independent of battery polarity.

Related JEE Advanced Physics questions

• What is the final velocity attained by the loop?
• A long coaxial cable is made up of two cylindrical conductors with radii a and b. The inner conductor carries a constant current i, while the outer conductor acts as the return path for the current. What is the self-inductance of a segment of the cable of length l?
• Determine the inductance per unit length for a loop created by connecting the ends of two infinitely long parallel wires, each with radius r, and separated by a distance d between their centers. Ignore the magnetic flux inside the wires and the effects at the ends.
• If the electromotive force is 10 V and the rate of change of current is calculated as 2.5 A/s, what is the self-inductance of the coil, given by L = e / (dl/dt)?
• The magnitude of the induced electric field in the orbit at any instant of time during the time interval of the magnetic field change is
• A semicircular loop of radius r is positioned on the axis of a large current-carrying circular ring of radius R (with R >> r). The loop is placed at an axial distance of R*sqrt(3) from the center of the ring, and the plane of the semicircular loop makes an angle of 53 deg with the plane of the ring. Find the mutual inductance M between the two coils.

⚔️ Practice JEE Advanced Physics free + battle 1v1 →