Question

A circular iron ring of mean diameter 25 cm and cross-sectional area 9 𝑐𝑚2 is wound with a coil of 100 turns and carries a current of 1.5 A. The relative permeability of iron is 2000. Calculate the amount of flux produced in the ring

Answer 1

$B=\frac{\mu \mu_0 N I}{\pi d},$

$\Phi=SB=\frac{\mu \mu_0 NI S}{\pi d}=432~\mu Wb.$