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 (From Eq).
`B_(0)=(mu_(0)I)/(2R)hati`
`B=(mu_(0)NI)/(2R)=(4pixx10^(-7)xx10^(2)xx1)/(2xx10^(-1))=2pixx10^(-4)=6.28xx10^(-4) T`