Give the expression for magnetic field due to a toroid.

(a)Using Ampere's circuital law,obtain the expression for the magnetic field due to a long solenoid at a point inside the solenoid on its axis. (b)In what respect is a toroid different from a solenoid?Draw and compare the pattern of the magnetic field lines in the two cases. (c)How is the magnetic field inside a given solenoid made strong?

Give the expression for magnetic field at a point on the equatorial line of a magnetic dipole.

Give the expression for magnetic field at a point on the axis of a short magnetic dipole.

Can a current carrying circular loop act as a magnetic dipole? Give the expression for the magnetic field at a point, due to a current carrying circular loop.

State the expression for magnetic field due to:- semi - infinite straight wire.

Derive an expression for the magnetic field produced by a toroid using Ampere's law.