Discuss Faraday's experiment of bar magnet and coil for generation of electric current in coil.

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(N/A) The figure shows a coil $C_{1}$ connected to a galvanometer $G$.
When the North-pole of a bar magnet is pushed towards the coil,the pointer in the galvanometer deflects,indicating the presence of electric current in the coil. The deflection lasts as long as the bar magnet is in motion. When the magnet is pulled away from the coil,the galvanometer shows deflection in the opposite direction,which indicates a reversal of the current's direction. The galvanometer does not show any deflection when the magnet is held stationary. Moreover,when the South-pole of the bar magnet is moved towards or away from the coil,the deflections in the galvanometer are opposite to those observed with the North-pole for similar movements.
Further,the deflection (and hence current) is found to be larger when the magnet is pushed towards or pulled away from the coil faster.
Instead,when the bar magnet is held fixed and the coil $C_{1}$ is moved towards or away from the magnet,the same effects are observed.
It shows that it is the relative motion between the magnet and the coil that is responsible for the generation (induction) of electric current in the coil.

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Discuss Faraday's experiment which shows that relative motion is not an absolute requirement for electromagnetic induction.

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Lenz's law is expressed by the following formula (here $e$ = induced $e.m.f.$,$\phi$ = magnetic flux in one turn and $N$ = number of turns).

If a coil of $40$ turns and area $4.0 \, cm^2$ is suddenly removed from a magnetic field,it is observed that a charge of $2.0 \times 10^{-4} \, C$ flows through the coil. If the resistance of the coil is $80 \, \Omega$,the magnetic flux density in $Wb/m^2$ is:

$A$ closed planar wire loop of area $A$ and arbitrary shape is placed in a uniform magnetic field of magnitude $B$,with its plane perpendicular to the magnetic field. The resistance of the wire loop is $R$. The loop is now turned upside down by $180^o$ so that its plane again becomes perpendicular to the magnetic field. The total charge that must have flowed through the wire ring in the process is

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