Find the angle of refraction and the critical angle of incidence

Question

The index of refraction of glass is 1.5. Find the speed of light in glass, the angle of refraction in glass, if the light is incident from water at an angle of 40°, the critical angle of incidence for a glass-water interface

Answer 1

Hi Dalia

Snell's law will help us to solve this question   sinθ1⁄sinθ2= n2/n1 = V1/V2

also we will use n = C / V  where C is light speed in space 3*10^8 m/s  and V is light velocity in material which has refractive index  n

sinθ1⁄sinθ2= n2/n1 ---> θ2= sin–¹(sin40 * 1.33/1.5)---> θ2=34.75º

to find speed of light in water V1 = C/n1 ---> V1 = 3*10^8 / 1.33 ----> V1 = 2.2556*10^8 m/s

now we can find speed of light in glass

V1/V2 = n2/n1 ----> V2 = V1 n1/n2 --> V2 = 2.2556*10^8 * 1.33/1.5 ----> V2 = 1.99999*10^8 m/s

 

Best