Normal-incidence Fresnel reflection and transmission
At normal incidence on a lossless nonmagnetic dielectric interface, the electric-amplitude reflection coefficient is r=(n₁−n₂)/(n₁+n₂).
Key knowledge
At normal incidence on a lossless nonmagnetic dielectric interface, the electric-amplitude reflection coefficient is r=(n₁−n₂)/(n₁+n₂). Power fractions are R=|r|² and T=4n₁n₂/(n₁+n₂)², so R+T=1; the transmitted amplitude is 2n₁/(n₁+n₂).
Values and equations
r=(n₁−n₂)/(n₁+n₂); R=r²; T=4n₁n₂/(n₁+n₂)²
- r
- Electric-amplitude reflection ratio
- R,T
- Reflected/transmitted power fractions
- n₁,n₂
- Dimensionless refractive indices
Conditions and scope
- Positive real indices, plane interface, no free surface charge/current and the common tangential electric-field convention.
- Oblique polarizations and absorbing or magnetic materials require their full impedance-dependent Fresnel relations; squared transmission amplitude alone is not the power fraction.
Sources · 1
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
Evidence and review
Classical Electromagnetism (2014): Fresnel relations: Tangential-field matching and reflection/transmission power formulas; normal-incidence limit of the displayed oblique relations.
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