Question

A circular coil of radius $10$cm, $500$ turns and resistance $2\Omega$ is placed with its plane perpendicular to the horizontal component of the earth's magnetic field. It is rotated about its vertical diameter through ${180}^o$ in $0.25$s. Estimate the magnitudes of the emf and current induced in the coil. Horizontal component of earth's magnetic field at the place is $3.0\times {10}^{-5}$T.

Answer 1

net flux through the coil: N x area of coil x field crossing perpendicular to the coil thus initial flux

$=15.7\times 3\times {10}^{-5}wb$ final flux$=0$

(because no part of flux is now perpendicular to it) thus change in flux

$=47.1\times {10}^{-6}w$be m find used+-(rate of change of flux)

$=1.88\times {10}^{-3}V$and current

=emf/resistance of coil

$=0.94\times {10}^{-3}A$