If the outer coil of the previous problem is rotated through 90° about a diameter, what would be the magnitude of the magnetic field B at the center?

A conducting circular loop of radius a is connected to two long, straight wires. The straight wires carry a current i as shown in figure. Find the magnetic field B at the centre of the loop.

Two circular coils of radii 5.0 cm and 10 cm carry equal currents of 2.0 A. The coils have 50 and 100 turns respectively and are placed in such a way that their planes as well as the centers coincide. Find the magnitude of the magnetic field B at the common centre of the coils if the currents in the coils are (a) in the same sense (b) in the opposite sense.

A circular loop of radius 20 cm carries a current of 10 A. An electron crosses the plane of the loop with a speed of 2.0 × 106 m s–1. The direction of motion makes an angle of 30° with the axis of the circle and passes through its center. Find the magnitude of the passes through its center. Find the magnitude of the magnetic force on the electron at the instant it crosses the plane.

Acircular loop of radius R carries a current I. Another circular loop of radius r (<<R) carries a current i and is placed at the center of the larger loop. The planes of the two circles are at right angle to each other. Find the torque acting on the smaller loop.