When a light ray travels from one medium, such as air, to another medium, such as water or glass, the speed of the light changes, and the direction that the ray is traveling changes. (This is why a fish under water is in a different position from the place at which it appears to be.) These changes are given by Snell’s law,

where c₁ is the speed in the first medium, c₂ is the speed in the second medium, and θ₁ and θ₂ are the angles shown in the figure.

In Exercises, assume that c₁ = 3 * 10⁸ m per second, and find the speed of light in the second medium.

θ₁ = 46°, θ₂ = 31°

C1 | C2 = sin 0 sin 0