Does the frequency of light changes when it go through a prism

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SUMMARY

When light passes through a prism, its frequency remains constant, which means the energy of the light does not change. However, the wavelength and speed of light are altered due to the refractive index of the prism material, typically glass. For example, red light with a wavelength of approximately 600 nm maintains its frequency while transitioning through the prism, resulting in the separation of visible light into its constituent colors. This phenomenon is a fundamental aspect of optics, as described by the relationship E = hf, where E is energy, h is Planck's constant, and f is frequency.

PREREQUISITES
  • Understanding of light properties, specifically wavelength and frequency
  • Familiarity with the concept of refraction and refractive index
  • Basic knowledge of optics and the electromagnetic spectrum
  • Awareness of the relationship between energy and frequency (E = hf)
NEXT STEPS
  • Research the principles of light refraction and the behavior of light in different media
  • Explore the electromagnetic spectrum and its relation to color perception
  • Study the historical experiments of Isaac Newton with prisms and light
  • Learn about the mathematical relationship between wavelength, frequency, and energy in light
USEFUL FOR

Students of physics, educators in optics, and anyone interested in the fundamental properties of light and its behavior when interacting with materials like glass.

Rico L
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I know the prism can separate the light into 7 colours, but my teacher said the frequency of light changes and so as the wavelength..



if he is right... this is the bit i am not sure about

if the frequency of the light changes when it passes through a prism, does it mean the energy also changes? if it does, does it mean that when the light goes through a prism, it changes into 7 different rays which that we don't regard them as the visible light because they all have different frequency and energy ?

please correct me

i am not even sure about my basic knowledge

many thanks
 
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The frequency does not change when light enters a prism, but the intensity and energy density of the light wave decreases somewhat due to partial reflection of the wave at the air-glass boundary.
 
fluidistic said:
Ok so basically a red light (wavelength of around 600 nm) entering say a prism whose refractive index is 1.5 becomes violet (wavelength of about 400 nm) in the prism, am I right?

No, the light is still red inside the prism. The frequency of the light (or energy of the associated photons, E = hf) is what fundamentally determines the color that we perceive. We usually relate color to wavelength (in vacuum or practically, in air) because wavelength is easier to measure directly.
 
jtbell said:
No, the light is still red inside the prism. The frequency of the light (or energy of the associated photons, E = hf) is what fundamentally determines the color that we perceive. We usually relate color to wavelength (in vacuum or practically, in air) because wavelength is easier to measure directly.

Ok thank you, amazing. :smile:
 
All the frequencies ( or colors) make up white light. The prism separates them. When Newton did this he also used a second prism placed so the spectrum coming out of the first prism was mixed back into white light which exited the second prism.
 
jtbell said:
...the associated photons, E = hf

Wait a minute. Using this same logic I get an associated momentum, p=h_bar k; an increase in momentum and an imaginary mass.
 

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