Faradays law of electromagnetic induction

Faraday's First Law

Any change in the magnetic field of a coil of wire will cause an emf to be induced in the coil. This emf induced is called induced emf and if the conductor circuit is closed, the current will also circulate through the circuit and this current is called induced current.
Method to change magnetic field:
1. by moving a magnet toward or away from the coil
2. by moving the coil into or out of the magnetic field.
3. by changing area of a coil placed in the magnetic field
4. by rotating the coil relative to the magnet.

Faraday's Second Law

It states that the magnitude of emf induced in the coil is equal to the rate of change of flux linkages with the coil. The flux linkages of the coil is the product of number of turns in the coil and flux associated with the coil.

Faraday Law Formula

Faraday's law

Consider a magnet approaching towards a coil. Here we consider two instants at time T1 and time T2.
Flux linkage with the coil at time, T1 = NΦ1 Wb
Flux linkage with the coil at time, T2 = NΦ2 wb
Change in flux linkage = N(Φ2 - Φ1)
Let this change in flux linkage be, Φ = Φ2 - Φ1
So, the Change in flux linkage = NΦ
Now the rate of change of flux linkage = NΦ / t
Take derivative on right hand side we will get
The rate of change of flux linkage = NdΦ/dt
But according to Faraday's law of electromagnetic induction the rate of change of flux linkage is equal to induced emf

Considering Lenz's Law

Where flux Φ in Wb = B.A
B = magnetic field strength
A = area of the coil

HOW TO INCREASE EMF INDUCED IN A COIL

• By increasing the number of turns in the coil i.e N- From the formulae derived above it is easily seen that if number of turns of coil is increased, the induced emf is also increased.

• By increasing magnetic field strength i.e B surrounding the coil- Mathematically if magnetic field increases, flux increases and if flux increases emf induced will also increased. Theoretically if the coil is passed through a stronger magnetic field, there will be more lines of force for coil to cut and hence there will be more emf induced.

• By increasing the speed of the relative motion between the coil and the magnet - If the relative speed between the coil and magnet is increased from its previous value, the coil will cut the lines of flux at a faster rate so more induced emf would be produced.