Moving Charges And Magnetism

Two concentric circular coils of 10 turns each are situated in the same plane. Their radii are \(20 \mathrm{~cm}\) and \(40 \mathrm{~cm}\) and they carry respectively \(0.2 \mathrm{~A}\) and \(0.3 \mathrm{~A}\) current in opposite direction. The magnetic field at the centre is (\(\mu_0=4 \pi \times 10^{-7}\) SI units)