Consider a tightly wound 100 turn coil of radius 10 cm, carrying a current of 1 A. What is the magnitude of the magnetic field at the centre of the coil ?

Explanation

Since the coil is tightly wound, we may take each circular element to have the same radius R = 10 cm = 0.1 m. The number of turns N = 100. The magnitude of the magnetic field is
`B= (mu_0 NI)/(2R) = (4pi xx 10^(-7) xx 10^2 xx 1)/(2 xx 10^(-1) ) = 2pi xx 10^(-4) = 6.28 xx 10^(-4)T`