What is the difference between diffraction and dispersion? What color diffracts the most?

[mrh125]

I've had a bit of trouble distinguishing differences between these two concepts. For dispersion I think of the pink Floyd dark side of the moon cover and basically light bends when it goes through different surfaces with different refractive indices and blue/violet light bends the most.
For diffraction I think of youngs slit experiment where light goes through a slit radiates, and interferes at various distances. What light diffracts the most? Is it blue/violet because it has the shortest wavelength or red because it has the longest wavelength?
Are my descriptions of diffraction and dispersion accurate? What is the difference between diffraction and dispersion? What color diffracts the most? What color disperses the most (bends?)

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[t5Nitro]

Different light waves have characteristic wavelengths and travel through a medium at different speeds. The wavelength of light determines how it will bend. A smaller wavelength corresponds to a higher index of refraction which is why, like you said, blue/violet bends the most. Set these two equations equal: v = (f)(wavelength) and v = c/n. You know wave speeds based on their characteristic wavelengths from the first equation.

Maybe someone else can chime in for diffraction. You've got the right experiment in mind, but I don't know if it's different in diffraction or not.

 

[brood910]

One example for dispersion is prism.
When you shine white light on it, you will see different colors coming out of the prism due to their different wavelengths.

n1/n2 = wavelength2/wavelength1

So, as you go from red to violet (decreasing wavelength), you will increase the index of refraction of prism.
As you increase n, you decrease the angle of refraction. So, violet will refract less when it enters the prism.
However, when it's leaving the prism, air has less n than prism, thus, it will refract more => disperse more.

Diffraction can be seen in slit experiments.
It happens when a wave spreads out after passing through a slit.
Spreading depends not just on the wavelength but also on the ratio of wavelength to the length of the slit.

Distance between maxima = (wavelength x distance between slit and screen)/length of slit

When the length of the slit is smaller than or comparable to wavelength, the wave will spread out noticeably.
If not, it wont spread out much.