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A 800 turn coil of effective area $0.05\ m^2$ is kept perpendicular to a magnetic field $5\times10^{-5}\ T$. When the plane of the coil is rotated by $90^\circ$ around any of its coplanar axis in 0.1 s, the emf induced in the coil will be:
Detailed Solution
$N=800$, $A=0.05\ m^2$, $B=5\times10^{-5}\ T$, $\Delta t=0.1\ s$; angle changes from $0^\circ$ to $90^\circ$.
$\Delta\phi=NBA\cos90^\circ-NBA\cos0^\circ=-NBA$
$=-800\times5\times10^{-5}\times0.05=-2\times10^{-3}\ Wb$
$e=-\frac{\Delta\phi}{\Delta t}=\frac{2\times10^{-3}}{0.1}=0.02\ V$