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
U_av = 1/2 ε₀ E²₀ = Electric field energy density
U_av = 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 = U_av = 1/2 ε₀cE²₀
= P_s/4πr²
where, P_s is power of the source and r is distance from the source.