The index of refraction of light in passing from a

The index of refraction of light in passing from a vacuum into water is 1.33. If the angle of incidence is 40°, determine the angle of refraction.

Some Indexes of Refraction

Medium ……………………………………… Index of Refraction^†

Water …………………………………………………………….…… 1.33

Ethyl alcohol (20°C) …………………..……………………..… 1.36

Carbon disulfide ……………………………….………………… 1.63

Air (1 atm and 0°C) ……………………………….………… 1.00029

Diamond …………………………………………………….…….… 2.42

Fused quartz ……………………………………………………… 1.46

Glass, crown …………………………………………….………… 1.52

Glass, dense flint ………………………….……………….….… 1.66

Sodium chloride …………………………..………………..…… 1.54

Light sound, and other waves travel at different speeds, depending on the media (air, water, wood, and so on) through which they pass. Suppose that light travels from a point A in one medium, where its speed is v₁, to a point B in another medium, where its speed is v₂. Refer to the figure, where the angle θ₁ is called the angle of incidence and the angle θ₂ is the angle of refraction. Snell’s Law, which can be proved using calculus, states that

The v_l/v₂ is called the index of refraction. Some values are given in the table shown to the right.