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Formula Sheets / Physics

Chapter 25

Electromagnetic Waves

Revise with flashcards Download this chapter (PDF) All Physics formulas (PDF)

Displacement current and properties Electromagnetic spectrum

Displacement current and properties

Displacement current
$I_{d} = ε_{0} \frac{d ϕ _{E}}{d t}$
Speed
$c = \frac{1}{μ _{0} ε _{0}},$ $\frac{E _{0}}{B _{0}} = c,$ $v = \frac{c}{n}$
Energy and intensity
$u = \frac{1}{2} ε_{0} E_{0}^{2}$ (average) $p = \frac{U}{c};$ $I = \frac{1}{2} ε_{0} c E_{0}^{2}$
Momentum and pressure
$p = \frac{U}{c};$ $P = \frac{I}{c}$ (absorbed) $, \frac{2 I}{c}$ (reflected)

Electromagnetic spectrum

radio $>$ microwave $>$ infrared $>$ visible $>$ UV $>$ X-ray $> γ$ (wavelength, longest first)
visible: $400$ – $700$ nm

Alternating Current Ray Optics