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

The volume of a cylinder of radius r and length h is

Two similar coils each of radius R and no. of turns N are lying concentrically with their planes at right angle to each other. The currents following in them are 1 A and sqrt3A respectively. What is the magnetic field at centre of the coils ?

Two concentric circular loops of radii 1 cm and 20 cm are placed coaxially. Find mutual inductance of the arrangement.

Total surface area of a hemisphere of radius r is :

A right circular cylinder just encloses a sphere of radius r Curved surface area of the cylinder.

A right circular cylinder just encloses a sphere of radius r curved surface area of the cylinder.

A spherical conduting shell of inner radius r_1 and outer radius r_2 has a charge Q. A charge q is placed at the centre of the shell. Write the expression for the electric field at a point x > r_2 from the centre of the spherical shell.

The curved surface area of a hemisphere of radius r is :