Notes

Results from Maxwell’s Equations…

Results from Maxwell’s Equations –
(i) Relation between amplitude of electric (E0) and the magnetic field (B0) is given by
E0 = cB0
where, speed of EM waves c = 1/√μ0 ε0 = 3 × 108 m/s
(ii) The average of energy density associated with electromagnetic wave is found to be
Uav = 1/2 ε0 E20 = Electric field energy density
Uav = 1/2μ0 B20 = Magnetic field energy density
(iii) Linear momentum (p) associated with electromagnetic wave is given by
p = U/c
where, U = Energy of the electromagnetic wave c = Speed of electromagnetic wave
(iv) Intensity (I) of EM wave is energy crossing through unit area in unit time,
I = Uav = 1/2 ε0cE20
= Ps/4πr2
where, Ps is power of the source and r is distance from the source.