Solenoid Field Strength Example

A solenoid is a conducting wire coated with an insulating material and wound tightly into a helical coil. Its magnetic field comes from the vector sum of the fields from each turn. For an ideal solenoid, the field inside depends directly on the number of turns per unit length and the current.

The...

Consider a solenoid with closely packed turns of wire so that its total length is greater than its radius.

A steady current flowing through this solenoid generates a magnetic field, which can be estimated by considering a rectangular Amperian loop through it. 

Applying Ampere's Law, the sum of the line integral of the magnetic fiel...