# Refraction of light:- “It is the phenomena of change in the path of light when it goes from one medium to another.”

When light ray goes from rarer to denser medium, it bonds towards the normal.

When light ray goes from denser medium to rarer medium, it goes away from the normal

# Absolute refractive index of a medium (µ):

“Absolute Refractive index of a medium is equal to the ratio of speed of light in vacuum to the speed of light in the medium”

i.e. µ = Speed of light in vacuum (c)/Speed of light in the medium (υ)

µ = c/υ           or        µ = υλ/υλ_m  ==>  λ_m = λ/µ

Note:- (i) Frequency (λ) of light remains same when light passes from one medium to another.

(ii) µ It is a dimension less quality and has no unit.

µ (for glass) = 1.5,   µ (for water) = 1.33