The equation of plane progressive electromagnetic wave can be written as E = E o sin Ω( t – x / c) and B = B o sin Ω( t – x / c). Where, Ω = 2πv
Electromagnetic waves are produced by accelerated charge particles.
Properties of EM Waves
( i) These waves are transverse in nature.
( ii) These waves propagate through space with speed of light, i. e., 3 * 10 8 m / s.
( iii) The speed of electromagnetic wave, c = 1 / √μ o ε o
where, μ oo is permittivity of free space,
∴ c = E o / B o
where E o and B o are maximum values of electric and magnetic field vectors.
[ According to Maxwell, when a charged particle is accelerated, it produces electromagnetic wave. The total radiant flux at any instant is given by,
p = q 2 a 2 / 6 πε o c 2
( iv) The rate of flow of energy in an electromagnetic wave is described by the vector S called the poynting vector, which is; defined by the expression,
S = 1 / μ o E * B SI unit of Sis watt / m 2.
( v) Its magnitude S is related to the rate at which energy is transported by a wave across a unit area at any instant.
( vi) The energy in electromagnetic waves is divided equally between electric field and magnetic field vectors.
( vii) The average electric energy density.