2.6 Refraction of Light

Question 1

Refractive index, n

Answer 1

n = c / v
velocity of light in a vaccum / velocity of light in the medium

Question 2

Snell’s law

Answer 2

n1 sinθ1 = n2 sinθ2
θ1 and θ2 are angles to the normal for light passing between medium 1 and medium 2; n1 and n2 are called the refractive indices of medium 1 and medium 2

Question 3

Critical angle, C

Answer 3

When light approaches the boundary between two media from the ‘slower’ medium, the critical angle is the largest angle of incidence for which refraction can occur. The refracted wave is then travelling at 90° to the normal.