Moving Charges And Magnetism

Two circular coils of radius '\(a\)' and '\(2 a\)' are placed coaxially at a distance ' \(x\) and '\(2 x\)' respectively from the origin along the \(\mathrm{X}\)-axis. If their planes are parallel to each other and perpendicular to the \(\mathrm{X}\) - axis and both carry the same current in the same direction, then the ratio of the magnetic field induction at the origin due to the smaller coil to that of the bigger one is: