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Homework Help: Speed of different color light

  1. Nov 21, 2006 #1
    when light pass through the spectrum,different colour of light appear on the screen.i want to ask if the freuquency of the different.color of light is different
    Is the speed different or is their speed all equal to 3x10*8?
    The level of the diffraction of these light is depend on frequency,speed or wavelength?
  2. jcsd
  3. Nov 21, 2006 #2


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    Homework Helper

    Yes, the different colours of light do have different wavelengths and frequencies. Red is the longer wavelength colours with low frequencies while blue colours have shorter wavelengths with higher frequencies.

    Rays of different colours do travel at the same speed in vacuum c, but in other media their speeds differ a bit. That is why rays of different colours do not refract the same - due to their differences in propagation velocities. That is how a prisma separates the colours - they refract differently through it. Red refracts the least, which means its speed changes to only slightly less than c and blue refracts the most, that is it slows down the most in glass.

    Diffraction is a different phenomena all together and we find that light "bends" around corners when it encounters an edge. Here we find that the longer wavelengths tend to "bend" more around an obstacle. That is red light will diffract more than blue light, which is opposite to what we find with refraction.
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