Electromagnetic Waves in Vacuum
; then it represents a wave.
Anywhere, if we find an equation of the form
In regions of free space, ρ=0, j = 0; i.e. when there is no charge or current;
Then Maxwell’s equations become
………………..(2)
These equations constitute a set of coupled 1st order , partial differential equation for E & B.
They can be decoupled by applying curl to (3) & (4);
So,
Since
We have
…….(7)
These equations are of 2nd order.
In vacuum, then each Cartesian componenet of E & B satisfies the 3 dimensional wave equation.
Hence Maxwell’s equation shows that vacuum supports the propagation of em waves travelling
at a speed.
Comparing (7) & (8), with the wave equation, we get
velocity of light.
Hence light is an em wave.
Lecture Notes By S.N.Dhal
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