Physics AS question! Diffraction gratings!

Jsut one question

With diffraction gratings you get orders right?
So between the first order and zero order the angle is theta.
Is the angle between the first order and second order also theta?
If this is true then is the angle between second order and zero order, 2 theta?
HELP! Its really silly but I jsut need an answer

Reply 1

Skipper12345

I'm assuming you know the equation nλ=dsinθ . When n represents the gap between the orders. So between orders 0and 1 n=1, between orders 0 and 2 n=2, and so on... Now answering your question, between orders e.g 4 and 5 n=1 because there is a gap of one order between them. This allows you to find θ when you don't know what number the orders given to you are (although you do know they are consecutive).
So based on this, you are right!
Hope this helped a little, but I'm tired, so apologies that it's not the clearest explaination! 😃

Reply 2

Kawaii289

NO, think about it. The length of the height between the order changes whilst the distance from the grating to the wall is unchanged. So the angle changes. Theta is different for each order, n , is used to compromise for this.

(edited 7 years ago)

Reply 3

Kawaii289

I edited some of my message, some sp mistakes.

Reply 4

CosineOfPi

if the distance between n=1 maxima and n=2 maxima = n=0 maxima and n=1 maxima then yes, you will be right.

Reply 5

Ayahhh

How do diffraction gratings work? And how is the path difference n*lambda? :/ And if the rays are all parallel (for a particular order) then how do they overlap and interfere? Thanks

Reply 6

Eimmanuel

Study Forum Helper

Original post by Someboady

It is a not silly question. If this is what is you are talking about the order.

d \sin \theta = n \lambda

Let say

d= 1.67 \times 10^{-6}

m and the wavelength is 380 nm.

So the angle between zero and 1st order is

\theta_{1} = \arcsin(\dfrac{380 \times 10^{-9}}{1.67 \times 10^{-6}}) = 13.2^\circ

The angle between zero and 2nd order is

\theta_{2} = \arcsin(\dfrac{2*380 \times 10^{-9}}{1.67 \times 10^{-6}}) = 27.1^\circ

\theta_{2} \ne 2 \theta_{1}

My answer to your question is NO.

Reply 7

Eimmanuel

Study Forum Helper

Original post by Ayahhh

How do diffraction gratings work? And how is the path difference n*lambda? :/ And if the rays are all parallel (for a particular order) then how do they overlap and interfere? Thanks

It may be good not hijack other people posting. It is good to know that you are hunger for understanding :smile:

The following website should help you know how diffraction grating work.
https://smartsite.ucdavis.edu/access/content/user/00002774/Sears-Coleman%20Text/Text/C36-40/39-7.html

Reply 8

Ayahhh

[QUOTE="Eimmanuel;69503080"]It may be good not hijack other people posting. It is good to know that you are hunger for understanding :smile:

The following website should help you know how diffraction grating work.
https://smartsite.ucdavis.edu/access/content/user/00002774/Sears-Coleman%20Text/Text/C36-40/39-7.html[/QUOTE]
You're rightt! Oops that really wasn't my intention, thanks for letting me know and thank you very much for the link