Consider a tightly wound 100 turns of a coil of radius 1 cm carrying a current of 1A . What is the magnitude of the magnetic field at the center of the coil ?

Number of turns on the circular coil, n = 100

Radius of each turn, r = 1.0 cm = 0.01 m

Current flowing in the coil, I = 1p A

Magnitude of the magnetic field at the centre of the coil is given by the relation,

| B | = μ₀ 2πnI / 4π r

Where,

μ₀ = Permeability of free space

= 4π × 10^–7 T m A^–1

| B | = 4π x 10^-7 x 2π x 100 x 1 / 4π x 0.01

       = 62.8 x 10^-4 T

Hence, the magnitude of the magnetic field is 62.8 × 10^–4 T.