Magnetic Field of a Solenoid

Solenoid is made out of current-carrying wire coiled into a series of turn. In a solenoid, a large field is produced parallel to the axis of the solenoid. More loops will bring about a stronger magnetic field.

Components of the magnetic field in other directions are cancelled by opposing fields from neighbouring coils. Outside the solenoid the field is also very weak due to this cancellation effect and for a solenoid which is long in comparison to its diameter, the field is very close to zero. Inside the solenoid the fields from individual coils add together to form a very strong field along the centre of the solenoid.

Derived from Ampere's Law;