Engineering Physics: Unit II: Electromagnetic Waves

Intensity of an Electromagnetic wave in vacuum

The magnitude of the average value of at a point is called the intensity of radiation at that point.

INTENSITY OF AN EM WAVE IN VACUUM

The magnitude of the average value of at a point is called the intensity of radiation at that point. The S.I unit of intensity is W/m2.

Let us consider the electric and magnetic field solutions

and

From eqn. (6)

The x-component (Direction of propagation) of the poynting vector is given as

The time average value of cos 2 (ωt - kx) is zero. So the average value of the poynting vector is

This is the intensity of an EM wave in vacuum.

Also intensity is represented as for localised sources as

Engineering Physics: Unit II: Electromagnetic Waves : Tag: : - Intensity of an Electromagnetic wave in vacuum

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Engineering Physics

PH3151 1st semester | 2021 Regulation | 1st Semester Common to all Dept 2021 Regulation