Find the total field energy of magnetic field stored per unit length inside a long cylindrical wire of radius R and carrying a current I.

The magnetic field on the axis of a long solenoid having n turns per unit length and carrying a current is

Magnetic field due to a long current-carrying wire Oersted's experiments showed that there is a magnetic field around a current-carrying wire. We determine the magnitude of magnetic field at some distance from a long stright wire carrying a current I.

The strength of magnetic field inside a long current-carrying straight solenoid is:

The strength of magnetic field inside a long current-carrying straight solenoid is: