A circular coil of wire consisting of 100 turns, each of radius 8.0 cm carries a current of 0.40 A. What is the magnitude of the magnetic field B at the centre of the coil?

The number of turns on the coil is given as 100

The radius of each turn is given as or

The magnitude of the current flowing in the coil (I) is given as

The magnitude of the magnetic field at the centre of the coil can be calculated by the following relation:

where is the permeability of free space equal to

hence,

The magnitude of the magnetic field is .