Magnetic field strength is the force experienced by a unit N-pole when placed at any point in a magnetic field is known as magnetic field strength or magnetizing force.

Magnetising force or magnetic field strength is denoted by H.

The unit of magnetic field strength is Newtons per weber or ampere turns per metre.

Mathematically magnetic field strength is given by,

H = number of turns × current / length

H = NI/l

Where, H = magnetic field strength

I = current

l = length

The unit of number of turns is turns, the unit of current is ampere and unit of length is metre. So the unit of magnetic field strength is ampere turns per metre.