# refraction vs bending in prism

#### MrNeuro

##### Full Member
7+ Year Member
Would it be correct to say that blue light has the smallest angle of refraction (in relation to the normal)

b/c snells states n1 sin(theta1) = n2 sin(theta 2)
1(theta 1) / n2 = sin theta 2

n2 is the largest for blue light and smallest for red light hence blue should have the smallest angle of refraction.... pretty sure this is right just looking for verification

#### chiddler

##### Full Member
10+ Year Member
yes. blue light diffracts the most and therefore has the highest n value and slowest speed.

remember violet is even slower and higher n value.

#### pm1

##### Full Member
Would it be correct to say that blue light has the smallest angle of refraction (in relation to the normal)

b/c snells states n1 sin(theta1) = n2 sin(theta 2)
1(theta 1) / n2 = sin theta 2

n2 is the largest for blue light and smallest for red light hence blue should have the smallest angle of refraction.... pretty sure this is right just looking for verification

I just posted a thread about this... apparently when dispersion happens there is an exception. Blue would have a smaller n and it will bend the most. However, I'm not quite sure the reasoning behind this exception..

#### chiddler

##### Full Member
10+ Year Member
I just posted a thread about this... apparently when dispersion happens there is an exception. Blue would have a smaller n and it will bend the most. However, I'm not quite sure the reasoning behind this exception..

generally speaking, a small n value means that there is very little diffraction going on (ie light bends less). a large n value means there is a lot of diffraction going on (ie the light bends more).

we both know that blue light bends more and therefore it has a larger n value than red light. the higher the frequency of light, the lower the velocity. therefore, purple moves the slowest, has the largest n value, and diffracts the most.

#### MrNeuro

##### Full Member
7+ Year Member
I just posted a thread about this... apparently when dispersion happens there is an exception. Blue would have a smaller n and it will bend the most. However, I'm not quite sure the reasoning behind this exception..

blue light will have a larger n

it comes from snells law

n1sin&#120563;1 = n2sin&#120563;2
sin&#120563;1 / sin&#120563;2 = n2 / n1 = v1/ v2 = &#955;1f1 / &#955;2f2

hence the dispersion angle is dependent upon either &#955; or frequency and a lower wavelength (blue) will have a higher refractive index and a smaller angle of refraction

#### pm1

##### Full Member

blue light will have a larger n

it comes from snells law

n1sin&#120563;1 = n2sin&#120563;2
sin&#120563;1 / sin&#120563;2 = n2 / n1 = v1/ v2 = &#955;1f1 / &#955;2f2

hence the dispersion angle is dependent upon either &#955; or frequency and a lower wavelength (blue) will have a higher refractive index and a smaller angle of refraction

yes, I'm pretty sure I'm mistaken too.. hehe I'm trying to figure this out. Is the angle of refraction and diffraction interchangeable? how come blue light has a larger n? why is it slower?

#### pm1

##### Full Member

generally speaking, a small n value means that there is very little diffraction going on (ie light bends less). a large n value means there is a lot of diffraction going on (ie the light bends more).

we both know that blue light bends more and therefore it has a larger n value than red light. the higher the frequency of light, the lower the velocity. therefore, purple moves the slowest, has the largest n value, and diffracts the most.

#### pfaction

##### Full Member
10+ Year Member
I'm gonna regurg what I know:

Higher index = more bend.

Higher frequency = higher index = more bend.

Lower lamda = higher index = more bend.

Violet is the slowest, highest index, bends the most.
Red is the fastest,lowest index, bends the least.

#### chiddler

##### Full Member
10+ Year Member

you need to organize your posts a little more nicely! people are more likely to read them that way.

i disagree with your premise that red light moves slowest.

notice that read light moves faster than the purple. is not meant to be taken as the literal speed of light of course, but, as the title of the image suggests if you check the url, it is meant for conceptualization.

#### pm1

##### Full Member
I'm gonna regurg what I know:

Higher index = more bend.

Higher frequency = higher index = more bend.

Lower lamda = higher index = more bend.

Violet is the slowest, highest index, bends the most.
Red is the fastest,lowest index, bends the least.

thanks!

This thread is more than 9 years old.

Your message may be considered spam for the following reasons: