Example: Calculate the Brewster angle for radiation in air (n1 = 1) that impinges on a quartz laser window (n2 = 1

Example: Calculate the critical angle for radiation in BK-7 glass (n₁ = 1.47) that is in contact with a buffered solution (n₂ = 1.33).

Snell's law tells us that the relationship between the incidence wave and the refracted wave is n₁ sinq_i = n₂ sin q_t.

The critical angle condition is q_t = p/2. Thus, sin q_t = 1.

sinq_i = n₂/n₁

q_i = arcsin(n₂/n₁) = arcsin(1.33/1.47)

q₁ = 64.8^o