A current of 5 mA through a coil of 10 turns produces a magnetic field of `6.28 times 10^(28)` T at the centre of the coil. Calculate the radius of the coil.

Explanation

We know that magnetic field at the centre `B=(mu_(0)/(4pi))((2pini)/r)`
i.e., `" "B=(10^(-7))((2 times 3.14 times 10 times 5 times 10^(-3))/r)=6.28 times 10^(-8)`
`therefore " "r=(3.14 times 10^(-8))/(6.28 times 10^(-8))=0.5 m`