Question

A flashlight beam makes an angle of 60 degrees with the surface of the water before it enters the water. in the water what angle does the beam make with the surface? (nwater = 1.33)
a. 22o


b. 0o


c. 30o


d. 60o


e. 68o

Answer 1

Answer;

= 22°

Explanation;

• According to Snell's law, the ratio of the sine of the angle of incidence to the sine of the angle of refraction is a constant. The constant value is called the refractive index of the second medium with respect to the first.

• Therefore; Sin i/Sin r = η

In this case; Angle of incidence = 90° -60° =30°, angle of refraction =? and η = 1.33

Thus;

Sin 30 / Sin r = 1.33

Sin r = Sin 30°/1.33

       = 0.3759

r = Sin^-1 0.3759

   = 22.08

   ≈ 22°