Question

a beam of monochromatic light strikes the interface between air and cedar oil (n=1.52) at angle θi and it follows the path show in the figure: the beam strikes the cedar oil water interface at angle a (a=12.8 ° ) and it enters water at angle θi. what is the incident angle θi ?

(N air = 1 and N water = 1.33)

θi = __________ °

Air Safflower oil Water 18,

Answer 1

Refractive index of water, nw = 1.33

Refractive index of cedar oil, nc = 1.52

Angle, a = 12.8⁰

From the diagram, the angle of refraction at the air safflower oil boundary is a.

Using Snell’s law for air- safflower oil boundary,

Sin θ_i = nc Sin a = 1.52 x Sin 12.8 = 0.3367

The incident angle, θ_i = Sin^-10.3367 = 19.7⁰

The incident angle, θ_i = 19.7⁰