Question

A layer of ethyl alcohol (n= 1.361) is on top of the water ( n=1.333) . At what angle relative to the normal to the interface of the two liquids is light totally reflected

Answer 1

Answer:

78.35°

Explanation:

THIS IS THE COMPLETE QUESTION BELOW;

A layer of ethyl alcohol (n = 1.361) is on top of water (n = 1.333). To the nearest degree, at what angle relative to the normal to the interface of the two liquids is light totally reflected?

From Snell's Law,

(ni)/(nr) = Sin (θr) / Sin (θi)

Where

θi = Angle of Incidence

θr = Angle of refraction

ni = Refractive index given for ethyl alcohol

nr = Refractive index of medium from which light is refracted

ni = 1.361

nr = 1.333

, θr = 90° ( Critical Angle is reffered to as Angle of Incidence at refracted angle of 90°) (θi = θc)

(ni)/(nr) = Sin (θr) / Sin (θi)

1.361/ 1.333 = Sin (90°)/ Sin( θc)

1.021= 0.894/ Sin( θc)

Sin( θc)= (0.9794

θc = Sin⁻¹ 0.9794)

θc = 78.35°