EM Waves formulas

Every formula JEE Advanced expects you to know for EM Waves, with the variables spelled out. Free, no sign-up. Read it before a mock, not during one.

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Formulas: 22
Subject: Physics
Exam: JEE Advanced
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EM Waves, every formula

22 formulas, typeset and free. Print it, or keep it open beside your practice.

Speed of light (vacuum)
$c = \frac{1}{μ _{0} ε _{0}} = 3 \times 1 0^{8} m/s$
Speed in a medium
$v = \frac{1}{μ ε} = \frac{c}{n}$
Field amplitude relation
$E_{0} = c B_{0}$
Instantaneous field ratio
$\frac{E}{B} = c$
Wave relation
$c = ν λ$
Displacement current
$i_{d} = ε_{0} \frac{d ϕ _{E}}{d t}$
Poynting vector
$S = \frac{1}{μ _{0}} (E \times B)$
Average electric energy density
$u_{E} = \frac{1}{4} ε_{0} E_{0}^{2}$
Average magnetic energy density
$u_{B} = \frac{B _{0}^{2}}{4 μ _{0}}$
Total average energy density
$u = \frac{1}{2} ε_{0} E_{0}^{2} = \frac{B _{0}^{2}}{2 μ _{0}}$
Intensity of an EM wave
$I = \frac{1}{2} ε_{0} E_{0}^{2} c$
Radiation pressure (absorbing)
$P = \frac{I}{c}$
Radiation pressure (reflecting)
$P = \frac{2 I}{c}$
Momentum of radiation
$p = \frac{U}{c}$
Directions in an EM wave
$E ⊥ B ⊥ c$
Ampere–Maxwell law
$\oint B \cdot d l = μ_{0} (I + ε_{0} \frac{d ϕ _{E}}{d t})$
Refractive index
$n = \frac{c}{v} = μ_{r} ε_{r}$
Spectrum order (increasing frequency)
$radio < micro < IR < visible < UV < X < γ$
Visible range
$400 nm < λ < 700 nm$
Photon energy
$E = h ν = \frac{h c}{λ}$
Energy carried per unit area per time
$⟨ S ⟩ = I$
Transverse nature
$EM waves are transverse (can be polarised)$

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EM Waves formulas

EM Waves, every formula

Speed of light (vacuum)

Speed in a medium

Field amplitude relation

Instantaneous field ratio

Wave relation

Displacement current

Poynting vector

Average electric energy density

Average magnetic energy density

Total average energy density

Intensity of an EM wave

Radiation pressure (absorbing)

Radiation pressure (reflecting)

Momentum of radiation

Directions in an EM wave

Ampere–Maxwell law

Refractive index

Spectrum order (increasing frequency)

Visible range

Photon energy

Energy carried per unit area per time

Transverse nature

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