What determines the colour? Frequency or wavelenght?

In summary, the color we see is determined by the frequency of light, which is related to its energy. The higher the frequency, the bluer the light, and the lower the frequency, the redder the light. This is known as the electromagnetic Doppler effect. The wavelength of light also plays a role, as it is inversely related to frequency. However, the wavelength can also be affected by the medium through which light passes. Overall, the energy of a photon is determined by its frequency and this is what determines the color we see.
  • #1
darkar
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What determines the colour? Frequency or wavelenght?
 
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  • #2
darkar said:
What determines the colour? Frequency or wavelenght?


Normally high frequencies correspond to small wavelengths, and this correspond to colours that are blue-shifted. In the EM-spectrum blue is high energy, and red is low energy. these colors come from the EM-variant of the Doppler-effect. An EM-spectrum can be "made" when reflected sunlight from a planet undergoed emission or absorption processes when passing through our atmosphere. So we will see lines that move to blue when a planet is moving towards us. lines will be moved to red when the planet moves away from us. This is the EM-Dopplereffect.
 
  • #3
Frequency times wavelength is the speed of light, so they are inversely related and either of them can be used.
 
  • #4
selfAdjoint said:
Frequency times wavelength is the speed of light, so they are inversely related and either of them can be used.

That's not a complete answer: the wavelength depends also on the medium through which the light passes. The color we see is determined by the frequency.
 
  • #5
It depends on the energy of the photons our retina cells receive. This energy would be [tex]E = hf[/tex] or [tex]E = hv/\lambda_{eye fluid}[/tex], with h plank's constant, and [tex]v = c/n_{eye fluid}[/tex] is the speed of light through the fluid in our eye.
 
  • #6
Just a note: The energy of a photon depends on its frequency, which does not change when light passes from one medium to another.
 

1. What is the relationship between frequency and wavelength in determining color?

The frequency and wavelength of light are inversely proportional to each other. This means that as the frequency increases, the wavelength decreases, and vice versa. The color of light is determined by its wavelength, so the higher the frequency, the shorter the wavelength and the more bluish the color appears. Conversely, the lower the frequency, the longer the wavelength and the more reddish the color appears.

2. Can different frequencies of light create the same color?

Yes, different frequencies of light can create the same color if they have the same wavelength. This is because the human eye perceives color based on the wavelength of light, not its frequency. For example, both red light with a frequency of 4.74 x 10^14 Hz and violet light with a frequency of 7.5 x 10^14 Hz have a wavelength of approximately 400 nanometers and will appear as the same color to the human eye.

3. How do objects appear to have different colors if they reflect the same frequency of light?

Objects appear to have different colors because they reflect different combinations of frequencies of light. For example, a red object appears red because it reflects mostly red light and absorbs all other colors. A blue object appears blue because it reflects mostly blue light and absorbs all other colors. The combination of frequencies that an object reflects creates the color that we perceive.

4. Can the frequency or wavelength of light change the color of an object?

Yes, the frequency or wavelength of light can change the color of an object. When light of a certain frequency or wavelength is shone on an object, the object will reflect that color and appear to be that color. Changing the frequency or wavelength of the light will change the color that is reflected by the object. For example, shining red light on a blue object will make it appear purple.

5. How does the human eye perceive color?

The human eye perceives color through specialized cells called cones, which are located in the retina. These cones are sensitive to different wavelengths of light and send signals to the brain, which interprets them as different colors. The three types of cones are sensitive to red, green, and blue light, and the combination of signals from these cones allows us to see all the different colors of the visible spectrum.

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