Exams › JEE Advanced › Physics

A conducting rod of length l = 0.2 m is suspended horizontally by two light vertical wires, each of length L = 0.1 m, in a vertical magnetic field of magnitude B = 1 T. The rod is displaced by an angle alpha = 60 deg from its equilibrium (lowest) position and released from rest. Find the potential difference between the ends of the rod when it passes through the lowest point.

1. Zero
2. 0.1 V
3. 0.2 V
4. sqrt(2)/10 V

Correct answer: Zero

Solution

The magnetic field is directed vertically, and at the lowest point the rod swings horizontally so each element of the rod moves horizontally as well. The force on charges (q*v cross B) acts along the vertical direction, not along the rod's length, so no EMF is induced along the rod and the potential difference is zero.

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 →