Electromagnetic Induction(Electric current generated by varying magnetic fields)

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Proved By Faraday and Henry

Magnet bought near coil

Coil with current bought near coil
connected to galvanometer

Coil connected to battery and
tapping key kept near coil connected to galvanometer

Current produced due to fluctuating current

Current produced due to relative motion

Produced due to change in Magnetic flux(ΦB)

ΦB=B.A=BAcostheta Wb

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Faradays Law of Induction

emf=-dB/dt volt

Lenz Law

Polarity of induced emf is such that it tends to produce current that opposes change in magnetic flux

Motional Electromotive Force

emf=BLv (where v is velocity of moving conductor L is length of conductor and B is external magnetic field)

Electricity and Magnetism are related

Energy Conservation

Current induced = BLv/R (where R is resistance )

Force on conductor=B^2L^2v/r

Power=B^2L^2v^2/R

dQ=dΦB/R

Eddy Current

Induced due to flux change

Opposes induced current

Used in

Magnetic braking in trains

Electromagnetic Damping

Inductance
(Electric current can be induced in coil due to flux change of another coil)

Self Inductance

Mutual Inductance

Change of flux in single isolated coil

EMF= -LdI/dt (Where L is coefficient of self inductance)

L=u0n^2AL (nL=total number of turns A=area of coil)

Change in flux due to current through
one of the two axial solenoids

EMF=-MdI/dt (Where M is coefficient of mutual inductance)

M=u0n1n2pi r^2 L (where r is radius of smaller solenoid n1,n2 is number of turns per length)

AC Generator

Coil rotated due to external force in magnetic field generates current in coil.

Generated Emf= NBA w(sinwt)

Emf,current max at 90 and 270 degrees