# Why does red light refract the least in dispersion ?

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#1
I get that red light has the largest wavelength.

Does this cause it to travel faster than all forms of visible light (as frequency remains the same in refraction) when it enters the new glass, thus causes it to refract the least ?

I can’t grasp the relationship with its wave speed that causes refraction, determined by its wavelength (compared to all other forms of visible light )
Thanks !!
0
2 years ago
#2
I think that this has something to do with refraction index. As far as I know the red light has the least one and thus the smallest refracting angle when red light goes through a prism.
1
2 years ago
#3
(Original post by lewis.h)
I get that red light has the largest wavelength.

Does this cause it to travel faster than all forms of visible light (as frequency remains the same in refraction) when it enters the new glass, thus causes it to refract the least ?

I can’t grasp the relationship with its wave speed that causes refraction, determined by its wavelength (compared to all other forms of visible light )
Thanks !!

Red light does not have the longest wavelength in the electromagnetic spectrum, however, if you are comparing the spectrum of visible light, red light has the longest wavelength.

If you refer to the link and see Figure 35.21, the graph shows how the refractive index changes with the wavelength. The refractive index of the various optical materials for the red light is usually lower.

Indeed, the red light would travel faster than blue light in the same optical materials and would refract the less than that of blue light.

I can’t grasp the relationship with its wave speed that causes refraction, determined by its wavelength (compared to all other forms of visible light )
It seems that you are referring what is shown in Figure 3 of the following link.
https://courses.lumenlearning.com/ph...of-refraction/
or
http://hyperphysics.phy-astr.gsu.edu...nd/refrac.html

If the explanation in the links is difficult, says what is/are the thing(s) that you don’t understand.
1
#4
(Original post by Eimmanuel)
Red light does not have the longest wavelength in the electromagnetic spectrum, however, if you are comparing the spectrum of visible light, red light has the longest wavelength.

If you refer to the link and see Figure 35.21, the graph shows how the refractive index changes with the wavelength. The refractive index of the various optical materials for the red light is usually lower.

Indeed, the red light would travel faster than blue light in the same optical materials and would refract the less than that of blue light.

It seems that you are referring what is shown in Figure 3 of the following link.
https://courses.lumenlearning.com/ph...of-refraction/
or
http://hyperphysics.phy-astr.gsu.edu...nd/refrac.html

If the explanation in the links is difficult, says what is/are the thing(s) that you don’t understand.
Thank you.

Would you mind telling me I would be correct in saying that that red light has the largest wavelength of all wavelengths of light on the visible spectrum, so when it enters more dense medium from a less dense one, it refracts the most because it experiences the smallest decrease in wavelength from the less to more dense medium so it refracts the least as it experiences the smallest change in speed.
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#5
(Original post by lewis.h)
Thank you.

Would you mind telling me I would be correct in saying that that red light has the largest wavelength of all wavelengths of light on the visible spectrum, so when it enters more dense medium from a less dense one, it refracts the most because it experiences the smallest decrease in wavelength from the less to more dense medium so it refracts the least as it experiences the smallest change in speed.
And it experiences the smallest change in speed as V= f* wavelength, but the wave’s frequency apparently remains constant when the wave refracts ?
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2 years ago
#6
(Original post by lewis.h)
And it experiences the smallest change in speed as V= f* wavelength, but the wave’s frequency apparently remains constant when the wave refracts ?
In refraction, there is a change in the speed of wave when it moves from medium 1 to medium 2. But there is no change in frequency.
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#7
(Original post by Eimmanuel)
In refraction, there is a change in the speed of wave when it moves from medium 1 to medium 2. But there is no change in frequency.
I see. Thank you.
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