The existence of electro-magnetic waves that propagate through the space in the form of varying electric and magnetic fields has been predicted by the four basic laws of electromagnetism which are called Maxwell’s equations.

**(i) Gauss’s law in electrostatics:** It states that the total electric flux through any closed surface is equal to times the net charge enclosed by

This equation is called Maxwell’s second equation. A direct consequence of this equation is that the magnetic monpoles do not exist.

**(iii) Faradays’s law of electromagnetic induction:** It states that the induced emf produced in a circuit is numerically equal to the rate of change of magnetic flux through it.

This equation is called Maxwell’s third equation.

The negative sign in this equation indicates that the induced emf produced opposes the rate of change of magnetic flux.

**(iv) Maxwell-Ampere circuital law** It states that the line integral of magnetic field along a closed path is equal to u_{0} times the total current (i.e., sum of conduction and displacement currents threading the surface bounded by that closed path) Mathematically,

This equation is called Maxwell’s fourth equation.

**(v) Lorentz:** The vector sum of electric force and magnetic force on any charged particle is called the Lorentz force.

The above five equations give a complete description of all electromagnetic interactions.

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