Two circular coils, one of radius r and the other of radius R are placed coaxially with their centres coinciding. For `Rgtgtr`, obtain an expression for the mutual inductance of the arrangement.

A right circular cylinder of radius r and height h (h > 2r) just encloses a sphere of diameter___

A small square loop of wire of side l is placed inside a large square loop of side L (Lgtgtl) . The loops are coplanar and their centres coincide. Find the mutual inductance of the system.

Two thin wire rings each having a radius R are placed at a distance d apart with their axes coinciding. The charges on the two rings are +q and -q . The potential difference between the centres of the two rings is

If a hemisphere of radius r unit is placed on one end of a right circular cyllinder of radius r unit and height h unit and a right circular cone of radius r unit and height h unit on the other end of the cylinder , then the total surface area of the new solid object will be pir (2h+2r+sqrt(h^(2)+r^(2))) sq - unit

The radius of each of two circular coils of single turn is r. The two coils are placed parallel to each other with a common axis. The distance between their centres is (r)/(2) . If equal current is sent through the two coils in the same direction, what will be the magnetic field (i) at the centre of each coil and (ii) at the mid point on the line joining the centres of the coils? What is the ratio of these two magnetic fields?

Two parallel coaxial circular coils of equal radius R and equal number of turns N, carry N carry equal currents I in the same direction and are separated by a distance 2R. Find the magnitude and direction of the magnetic field produced at the mid point of the joining their centres.

A circular copper ring of radius r, placed in vacuum, has a charge q on it. Find out the electric fields at the centre of the ring.

Two indentical circular coils, P and Q each of radius R, carrying currents 1A and sqrt(3)A resepectively. Are placed concentrically and perpendicular to each other laying in the XY and Yz planes. Find the magnitude and direction of the net magnetic field at the centre of the coils.