Lenses

Refractive index

Measurement of how much light passes through (n)

How to calculate refractive index

n=c/v

n = speed of light in a vacuum / speed of light in the material

What is Snell’s law

n₁sinθ₁=n₂sinθ₂

refractive index 1 x angle of incidence of ray in material 1 =

refractive index 2 x angle of refraction of ray in material 2

Where does light bend when n1 is more optically dense from n2, and vice versa

n1>n2, light bends away from the normal

n1<n2, light bends towards the normal

Critical angle

When the angle of refraction is 90^o and the light is refracted along the boundary

Critical angle equation

sinC = 1/n (where the first material is air)

Total internal reflection

Angle of incidence is greater than the critical angle and n1 is greater than n2

Principal focus

Converging - light rays parallel to the principal axis are focused

Diverging - Where the rays appear to come from