Electromagnetism - University of Manchester
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Electromagnetism PHYS20141 Paul.Campbell-3@manchester.ac.uk Schuster 4-11
Transcript of Electromagnetism - University of Manchester
PHYS20141 Electromagnetism2
Week 11
- EM waves in the presence of current
- Good conductors and skin depth
- Plasma
- Reflection of EM waves at a perfect conductor
Maxwell’s equations
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Maxwell’s equations in the
presence of current only
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Conductors:
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Skin depth :
Skin depth
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d
Intensity, |E0|2 Intensity, |E0|
2exp[-2z/δ]Conductor, σ
Skin depth
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Plasma
State of matter which is partially ionized and electrons
move under the influence of the electric field –
ignore magnetic field.
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Hence :
Reflection (infinite thickness)
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y
x
y=0
Perfect conductor, E = 0
θI θR
Incident wave, EIReflected wave, ER
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Reflection of EM waves
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Polarization
- Linear polarization
- Circular polarization
- Stokes parameters
Linear polarization
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Circular polarization
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Clockwise rotation (when viewed
from source), “right-handed”
polarization.
Summary of polarization
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Stokes parameters
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Notes on Stokes Parameters
� For a monochromatic plane wave
� Fraction of linear polarization:
� Fraction of circular polarization:
� Alternative forms:
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