A circular coil of radius R having N number of turns carries a steady current I The magnetic inducti...........

General Science (NDA) Physics

A circular coil of radius R having N number of turns carries a steady current I. The magnetic induction at the centre of the coil is 0.1 tesla. If the number of turns is doubled and the radius is halved, which one of the following will be the correct value for the magnetic induction at the centre of the coil?

0.05 tesla

0.2 tesla

0.4 tesla

0.8 tesla

Explanation:

The formula for magnetic induction with N number of turns is
$B_{1}=\frac{\mu _{o}N^{_{1}}I}{2R_{1}}$
When N2 = 2N₁and R2 = 2R₁
B₂= 4x 0.1 = 0.4 tesla