# Diffraction Grating lab

You find two unlabelled diffraction gratings in your lab. From purchase records, you know that one grating has 5000 lines/cm, while the other has 10 000 lines/cm. Given the following equipment, describe how you would determine which is the grating with 10 000 lines/cm:
• Red laser
• detection screen
• the two unknown diffraction gratings
describe what difference you would observe.
n = d sin(theta)
d=1/5*105 = 2*10-6
d=1/1*106= 10-6

At what angle would you see the first maximum for the 5000 line grating? At what angle would you see the first maximum for the 10000 line grating?

If you had a screen, say, 10 m away from the 5000 line grating, how far would the central maximum be from the first, second and nth maximas? What about for the 10000 line grating?

You missed a $$\lambda$$ in your equation. It should read

$$n \lambda = d sin(\theta)$$

Anyway, what do you expect the difference between the interference patterns to be when you shine the laser on the two different gratings? Where is the first order (n=1) maximum with each grating?

Edit:
And I see oedipa maas just posted similar remarks. . .

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thats what i got
suppose the wavelength= 1cm = 1*10^-9
and m= 1
when d= 2*10^-6 m/line
theta= 0.029

when d= 10^-6
theta= 0.057
that's all what i got