Explain Energy and Momentum in Electromagnetic Waves
Since for an EM wave B = √(μƐ) E, the electric and magnetic contributions to energy density are equal, (Ɛ E2)/2 = B2/2μ and so…
Mathematics
Explain EM Waves in Vacuum and Linear Media
Starting with Maxwell’s equations, we shall shortly derive the wave equations for the electric and magnetic fields and show that they predict the existence of…
Explain Standing Waves on Lossless Transmission Line
Unless the line is terminated with the characteristic impedance there will also be reflected waves traveling in the -x direction, and the wave amplitude will…
Explain Lossless Transmission Lines Equations
We will only discuss lossless transmission lines, i.e. where there is no resistance present between or along the conductors. Then the equivalent circuit of infinitesimal…
Explain Transmission Lines with Two Parallel Conductors
Transmission lines are electrical cables which consist of two parallel conductors of uniform cross section, usually separated by a dielectric, and which are designed to…
Explain Conservation of Momentum
One can derive the equation describing conservation of momentum from the force on a particle of charge q, as given by Lorentz force equation F…
Explain Conservation of Energy
In 1884 English physicist John Henry Poynting (1852-1914) published his theorem, which is an expression of the law of conservation of energy in electrodynamics. We…
Explain Displacement Current
We can use Gauss’ law to replace p = Ɛ0 Δ • E in the continuity equation to get Δ. J + [ϐ (Ɛ0 Δ…
Maxwell’s Equations in Vacuum
Maxwell modified Ampere’s law in 1865 to make it apply to electrodynamics by adding the displacement current to the current. Replacing Ɛ E with D…
Explain Maxwell’s Equations
Scottish theoretical physicist James Clerk Maxwell (1831-1879) unified electricity and mag-netism into classical electrodynamics. A logical development of his equations follows. In going from electrostatics…
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