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 .