Two concentric circular coils having radii r₁ and r₂, (r₂< < r₁ ) are placed co- axially with centres coinciding. The mutual induction of the arrangement is (Both coils have single turn) ( ₀= . permeability of free space)

Step-by-step solution

If current I ₁ flows in the coil of radius r ₁ , the magnetic field at the centre is given by B ₁= ₀ I ₁ 2 r ₁ The magnetic flux passing through the coil of radius r ₂ will be ₂= B ₁ r ₂²= _ o I ₁ 2 r ₁ r ₂² Mutual inductance M= ₂ I₁ = ₀ r₂² 2 r₁