A circular coil of 200 mm diameter is made of 100 turns of thin wire and carries a current of 50 mA. Find the magnetic field induction in the centre of the coil and on the coil' axis 100 mm away from its centre.

Answer

`3.1 xx 10^(-5)T; 1.1 xx 10^(-5)T`

Explanation

Neglecting the thickness of the wire as compared with the radius of the coil and the other dimensions, we obtain an expression `B=(mu_(0)iwa^2)/(2(a^2+h)^(3//2))`
where to is the number of turns, a is the radius of a burn, and h is the distance from the centre to the point on the axis of the coil where the field is to be determined.