State and explain Faraday's law of electromagnetic induction.

(N/A) Faraday's law states: "The magnitude of the induced emf in a circuit is equal to the time rate of change of magnetic flux through the circuit."
Mathematically, the induced emf $\varepsilon$ is given by:
$\varepsilon = -\frac{d \phi_{B}}{d t}$ ... $(1)$
The negative sign indicates the direction of $\varepsilon$ (Lenz's Law), which opposes the change in magnetic flux.
In the case of a closely wound coil of $N$ turns, the change of flux associated with each turn is the same. Therefore, the expression for the total induced emf is given by:
$\varepsilon = -N \frac{d \phi_{B}}{d t}$ ... $(2)$
The induced emf can be increased by increasing the number of turns $N$ of the coil or by increasing the rate of change of magnetic flux $\frac{d \phi_{B}}{d t}$.