Law of Electromagnetic Induction
1. First law—Whenever there is change in magnetic flux linked with the coil changes induced emf produced in the coil. The induced emf lasts as long as the change in magnetic flux linked with the coil.
2. Second law—Rate of change of magnetic flux linked with the coil is directly proportional to the induced emf.
If ϕ1 is the initial flux at t1
If ϕ2 is the final flux at t2
For all practical purposes,
K = 1 ....(3)
For small time,
From Eqn (5)
direction of induced emf is not well definition emf without direction is useless. The direction of emf was calculated by lenz. The corrected form is called Faraday lenz law.
Faraday-lenz correction—Hence, emf induced in the coil opposes its cause, In other words direction of emf is opposite to change in magnetic flux takes place in the coil.
The magnetic of induced emf in a circuit is equal to the time rate of change of magnetic flux through the circuit. Mathematically, the induced emf is given by
The negative sign indicates the direction of E. In case of a closely wound coil of N turns, change of flux associated with each turn, is the same. Therefore the expression for the total induced emf is given by
The induced emf can be increases by increasing the number of N turns of a closed coil.
