Exams › JEE Advanced › Physics

A conducting circular loop is placed in a uniform magnetic field B perpendicular to the plane of the loop. The radius of the loop increases with time as R = R0 + t. What is the magnitude of the emf induced in the loop?

1. 2*pi*(R0 + t)*B
2. pi*(R0 + t)*B
3. pi*(R0 + t)²*B
4. zero

Correct answer: 2*pi*(R0 + t)*B

Solution

Flux Phi = B*A = B*pi*R². Then emf = dPhi/dt = B*pi*2R*(dR/dt). Since R = R0 + t, dR/dt = 1, so emf = 2*pi*B*(R0 + t). The magnitude is 2*pi*(R0 + t)*B.

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 →