Does speed of light depend on the wavelength or frequency of it?

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SUMMARY

The speed of light in a vacuum is a constant, denoted as c, and does not depend on wavelength or frequency. The relationship between speed, frequency (f), and wavelength (λ) is defined by the equation c = fλ, indicating that if frequency increases, wavelength decreases proportionally, maintaining a constant product. However, in mediums like glass or water, the speed of light can vary with frequency, which subsequently fixes the wavelength. This means that in such mediums, the speed, frequency, and wavelength are interdependent.

PREREQUISITES
  • Understanding of the equation c = fλ (speed of light equation)
  • Basic knowledge of wave properties (frequency and wavelength)
  • Familiarity with the concept of light propagation in different mediums
  • Knowledge of the distinction between vacuum and medium effects on light speed
NEXT STEPS
  • Research the implications of light speed in different mediums, focusing on glass and water
  • Explore the concept of refractive index and its effect on light speed
  • Study the principles of wave-particle duality in light
  • Investigate advanced topics in optics, such as dispersion and its relationship to frequency
USEFUL FOR

Students of physics, optical engineers, and anyone interested in the fundamental properties of light and its behavior in various environments.

nineteen
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I heard that the speed of light doesn't depend on the wavelength or frequency of it, how does it happen? I don't understand it because the ultimate equation is c = fλ (where c is the speed of velocity of light, f is the frequency and λ is the wavelength of it...).
 
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As the frequency increases the wavelength decreases, so their product doesn’t change.
 
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nineteen said:
I heard that the speed of light doesn't depend on the wavelength or frequency of it
Where did you hear this? It's wrong in general.

The speed of light is a constant in vacuum. There isn't really an answer to why that is at a B level - it's just the way the world works. In terms of your ##c=f\lambda##, it means that a light wave of frequency ##f## must have wavelength ##c/f##. You don't get to choose both ##f## and ##\lambda##.

For light in a medium, such as glass or water, the speed of light does vary with frequency. But again, this means that once you've chosen a frequency and a medium the wavelength is fixed, because you are not free to choose the speed and the frequency independently.
 
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