bradders10101
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I am working through the 2005 Cambridge University Press, worksheets for AS physics Revision, for the upcoming exams. I am on worksheet 17.

I am stuck on question 8 which states:

"Monochromatic light is incident normally at a diffraction grating with 60 lines per mm. The tenth order maximum is observed at an angle of 19 degrees."

a) Calculate the spacing between the centres of adjacent lines (mm)
b) the wavelength of incident light.

If anyone could talk me through this or find the attached mark scheme for the test, I would be extremely grateful.

Thanks, James
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Pangol
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(Original post by bradders10101)
I am working through the 2005 Cambridge University Press, worksheets for AS physics Revision, for the upcoming exams. I am on worksheet 17.

I am stuck on question 8 which states:

"Monochromatic light is incident normally at a diffraction grating with 60 lines per mm. The tenth order maximum is observed at an angle of 19 degrees."

a) Calculate the spacing between the centres of adjacent lines (mm)
b) the wavelength of incident light.

If anyone could talk me through this or find the attached mark scheme for the test, I would be extremely grateful.

Thanks, James
(a) 60 lines per mm = 60,000 lines per metre (this number is usually called N). Do you know the relationship between N and d, the grating spacing?

(b) If you can get an answer to (a), you can now use the diffraction grating equation, usually written as nx = d sin(theta) (I've used x instead of lambda, can't be bothered with Latex!).

Although I think this last equation should be written as nx = d sin(theta_n), to emphasise the link between the order and the angle.)
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