Find the angle of refraction of light incident on a water surface

Question

Find the angle of refraction of light incident on a water surface at an angle of incidence of 52°. What is the speed of light in water?

Answer 1

HI Dalia

we can use Snell's law to solve this problem 

 

Snell's law states    sin(θ1)/sin(θ2) = V1/V2 = n2/n1

 

where θ1 is light angle in air, V1 light velocity in air ( V1 = 3 * 10^8 m/s), and n1 is reflective index of air equals 1 

 

and θ2 is light angle in water after refraction, V2 is light velocity in water, and n2 is reflective index of water equals 1.33, ( u can find n from tables)

 

sin(52)/sin(θ2) = 1.33/1-----> sin(θ2) = sin(52)/1.33---> sin(θ2) = 0.592489   to find θ2 we need to take inverse sine by using calculator     θ2 = inv sine(0.592489) ------> θ2 = 36.33°

 

now to calculate V2;   V1/V2 = n2/n1-----> V2 = V1/1.33 ----> V2=(3*10^8)/1.33---->

V2 = 2.2556*10^8 m/s   light velocity in water

 

Best