Refraction & Prisms: Angle of Incidence Explained

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In summary, the conversation discusses the relationship between the angle of incidence and angle of refraction in a prism. This is explained through the geometry of a triangle formed by the light ray and the prism borders. The sum of the interior angles of this triangle is 180 degrees, with one angle being 60 degrees. Another way to understand this is by looking at the triangle formed by the prism's apex and the angles of 90- i and 90-r. This triangle also has a sum of 180 degrees.
  • #1
Alameen Damer
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That is a page from my textbook. The book mentions that the angle of incidence on the right side when added with the angle of the refraction equals 60 degrees. Why is that?
 
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  • #2
Consider the triangle formed by the light ray in the prism and the two prism borders. The sum of the interior angles is 180°, and one angle is 60°. Everything else follows from geometry with the right angles there.
 
  • #3
Which triangle? If you mean the one formed by the refracted ray, it is not a right angle triangle.
 
  • #4
Triangle ABC:
$$
\angle A + \angle B + \angle C = 180^0
$$
Or triangle formed by B, C, and the prism's apex.
 

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  • #5
Another way to look at it. The very top triangle has one angle of 60°. The other two angles are 90- i and 90-r etc. etc...
 
  • #6
sophiecentaur said:
Another way to look at it. The very top triangle has one angle of 60°. The other two angles are 90- i and 90-r etc. etc...
That is the triangle I meant.
And the sum of those three angles is 180 degrees.
 

What is refraction?

Refraction is the bending of light as it passes through a transparent medium, such as air, water, or glass. This bending occurs because light travels at different speeds in different mediums.

How does a prism work?

A prism is a triangular-shaped piece of glass that has two flat surfaces and three angled surfaces. When light enters the prism, it is bent, or refracted, as it passes through the different angles. This causes the light to separate into its component colors, creating a rainbow-like effect.

What is the angle of incidence?

The angle of incidence is the angle at which a ray of light hits a surface, such as a prism. It is measured between the incoming ray and the normal, or perpendicular, to the surface. This angle is important in understanding how light is bent and refracted by different mediums.

What is the relationship between the angle of incidence and the angle of refraction?

The angle of incidence and the angle of refraction are related by Snell's law, which states that the ratio of the sine of the angle of incidence to the sine of the angle of refraction is equal to the ratio of the speeds of light in the two mediums. This relationship helps us predict how light will be bent as it passes through different materials.

What are some practical applications of refraction and prisms?

Refraction and prisms have many practical applications, such as in eyeglasses, microscopes, and telescopes. They are also used in photography, optical instruments, and fiber optics technology. Prisms are also commonly used in classrooms to demonstrate the properties of light and color.

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