Fresnel's formula

Fresnel's formula

Formula used to determine the amount of light reflected at the interface between two transparent media. The reflection iswhere n₁ is the index of refraction of the first medium and n₂ that of the second medium. For a lens surface in air, the percentage of light reflected is given byExample: the reflection from the two surfaces of a glass lens made of crown (n = 1.523) is equal to 8.6%. See ghost image; surface reflection.

Table F3 Percentage of light reflected in normal incidence r at the surface of several transparent substances of varying refractive indices, in air
refractive index	ρ (%)
1.333	2.04
1.4	2.78
1.45	3.35
1.5	4.0
1.523	4.3
1.55	4.65
1.6	5.32
1.65	6.02
1.7	6.72
1.75	7.44
1.8	8.16