Understand the refraction of light

by iw_azeheb 03 Mar

Have you seen that when you put some object inside a glass of water it gets distorted? When you put your feet in the pool they look bigger? And that sometimes a river seems to be very shallow, but actually it’s too deep? You can blame the refraction of light for these illusions.

Refraction of light occurs when it passes from a transparent place to another transparent one, for example, from air to water. The light wave doesn’t have its frequency altered, but it’s propagation velocity and wavelength do. That is why the direction of the light ends up suffering a deviation, causing the illusion in our eyes that the object between these means is different from normal. However, the phenomenon of refraction occurs only if the velocity of propagation of light between the ways is different.

The speed of light in the air is greater than in water or glass. When the light passes from one way to another, and its speed reduces, the angle of refraction approaches the normal; And when it is greater (for example, from water to air) it moves away:

It is possible to calculate the angle of refraction, as well as the refractive index of the medium, through Snell’s Law:

N1 sinθ1 = n2 sinθ2

Since θ are the incidence and refraction angles and the n is the refractive index in each medium.

The absolute refractive index in each case is inversely proportional to the speed of light in this same one and the equation representing is:

When the angle of incidence of light is 0 degrees, there is refraction, but there is no change of direction.

The optical illusion that the refraction of light produces causes us not to know exactly where the object we see is, so it is important to be aware of the effects of refraction in order to make the necessary adjustments. For example, during a fishery is important to understand that the fishes are not at the point you see, or at sunset, when what we see is the light refracted by the particles of our atmosphere and the real sun has set itself for some time.

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