Why Does Blue Light Bend More than Red Light Through a Prism?

In summary, the speed of light is slower in various materials than it is in a vacuum or outer space. This causes the light to be bent or refracted according to Snell's Law and the index of refraction of the material. Shorter wavelength light is bent more than longer wavelength light when put through a prism.
  • #1
erjkism
54
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i was just wondering why blue light is bent more than red light when light is passed through a prism. Could someone explain this?

Also, when light goes through glass with an index of refraction>1, why is the angle of refraction less than the angle of incidence?
 
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  • #2
From http://www.school-for-champions.com/science/light_dispersion.htm

Dispersion of Light
by Ron Kurtus (8 September 2005)

The speed of light is slower in various materials than it is in a vacuum or outer space. When the light passes into a material at an angle, the light beam is bent or refracted according to Snell's Law and the index of refraction of the material. But also, the speed of light through a material varies slightly with the wavelength or frequency of the light. Thus, each wavelength is refracted at a slightly different angle when passing through a material at an angle. This spreading out of the beam of light is called dispersion or chromatic dispersion. This can be seen when sunlight passes through a glass prism. Dispersion can cause problems with camera lenses and must be minimized.
 
  • #3
thanks for that site... but now i am curious to find out why shorter wavelengths produce higher index of refraction.
 
  • #4
Shorter wave lengths have greater energy
 
  • #5
yea, i know that. but why are they slowed down more than longer wavelengths when put through a prism.
 
  • #6
erjkism said:
i was just wondering why blue light is bent more than red light when light is passed through a prism. Could someone explain this?
It is bent more because the refractive index of a dielectric such as glass is usually higher for shorter wavelengths. The reason that it is higher is tied in with how an EM wave polarises atoms within the medium as it propagates. The details of this are non-trivial, I suggest maybe reading up on the Kramers-Kronig relations and importantly, how they are derived.

Claude.
 

1. Why does blue light bend more than red light through a prism?

Blue light bends more than red light through a prism because it has a shorter wavelength and higher frequency. This causes it to interact more strongly with the atoms in the prism, resulting in a greater amount of refraction.

2. How does a prism bend light?

A prism bends light through refraction, which is the change in direction of a wave as it passes through a medium. When light enters a prism, it slows down and changes direction based on its wavelength, causing it to separate into different colors.

3. What is the relationship between wavelength and refraction?

The relationship between wavelength and refraction is that shorter wavelengths (such as blue light) will refract more than longer wavelengths (such as red light). This is due to the difference in speed at which the different wavelengths travel through a medium.

4. Can other colors of light also be refracted by a prism?

Yes, all colors of light can be refracted by a prism. The amount of refraction will vary based on the wavelength of the light. For example, green light will bend less than blue light but more than red light.

5. What other factors can affect the amount of refraction in a prism?

The angle at which the light enters the prism, the material of the prism, and the temperature can all affect the amount of refraction in a prism. Additionally, the shape and size of the prism can also impact the refraction of light passing through it.

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