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# Diffraction grating help watch

1. Light of wavelength λ is incident on a diffraction grating of slit seperation 4λ. What is the angle between the second order maximum and the third order maximum of the diffracted light?

I would presume i would have to use the diffraction grating formula nλ=dsinx, but not sure how to answer the question with it.

thanks if you can help,
2. They told you d = 4λ...
3. simon what past paper was that off
4. cant remember, i will find out and attach a link for you
5. its question 7 on

http://www.aqa.org.uk/qual/gceasa/qp...W-QP-JAN08.PDF

i will have a look at it again in the moment
6. From what you've given:

nλ=dSinx
nλ=4λSinx
2λ/4λ=Sinx
Sin^-1(2λ / 4λ) =x
(Thats for Second maximum, do the same for third maximum)

(Let λ be 6.5x10^07)

Second max. 30 degrees
Third max 48.6 degrees
Then subtract your second maximum anagle value from your third maximum, and you should get your answer to be 18.6 degrees, and therefore B

Jez
7. Or you just do:

nλ = 4λsinx
sinx = n/4

So angular separation is arcsin(3/4) - arcsin(1/2)

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Updated: November 11, 2008
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