Embibe Experts Solutions for Chapter: Magnetic Effect of Current, Exercise 1: CUSAT CAT 2017

A charged particle moves through a magnetic field in a direction perpendicular to it. Then the

The magnetic field at the centre of circular coil of radius $r$ carrying current $I$ is ${\mathrm{B}}_1$. The field at the centre of another coil of radius  $2r$ carrying same current $I$ is ${\mathrm{B}}_2$. The ratio of $\frac{{\mathrm{B}}_1}{{\mathrm{B}}_2}$ is