PHYS 012A Lecture Notes - Lecture 25: Electromagnetic Radiation, Magnetic Monopole, Displacement Current
12 Jun 2018
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Chapter 34 – Electromagnetic Waves
Modifiatios to Apee’s La
- Maxwell modified the equation to include time-varying electric fields by adding another term, the
displacement current,
Maell’s Euatio
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Law 1 – Gauss’ La →relates electric field to the charge distribution that creates it
Law 2 – Gauss’ La i Magetis → # of magnetic field lines that enter a closed volume must equal the
number that leave the volume. No magnetic monopoles.
Law 3 – Faada’s La of Idutio → describes the creation of an electric field by a time-varying magnetic
field. The emf which is the line integral of the electric field around any closed path, equals the rate of
change of the magnetic flux through any surface bounded by that place. One consequence is the current
induced in a conducting loop placed in a time-varying magnetic field.
Law 4 – Ampere-Maxwell Law → describes the creation of a magnetic field by a changing electric field and
by electric current. The line integral of the magnetic field around any closed path is the sum of times
the net current through that path and times the rate of change of electric flux through any surface
bounded by that path.
Lorentz Force Law
- Once the electric and magnetic field are known, the force acting on a particle of charge q can be
found.
Maxwell’s Euations + Loentz Foce Law → describe all classical electromagnetic interactions
So why are the alled Maell’s Euatios?
- Because Maxwell showed that electromagnetic waves are a natural consequence of the
fundamental laws expressed in these four equations.
Electromagnetic Waves
- I ept spae hee = ad I=, the last euatios Faada’s and A-M Law) become
Electromagnetic Waves
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