pointer15
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https://isaacphysics.org/questions/grating_spectrum
For part b,c how can I find the wavelength if I don't know the order (n) for the specific angles at which the maxima occur if (n x lambda = d x sin theta))
I know that shorter wavelengths diffract less.
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cflau_
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I am not sure, but you can calculate the order with the given information for each colour. For example, for violet, we have
 d \sin \theta_1 = m \lambda
 d \sin \theta_2 = (m+1) \lambda
By solving two equations for the two unknowns (\lambda\text{ and }m) you can get both the wavelengths and the order.
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pointer15
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(Original post by cflau_)
I am not sure, but you can calculate the order with the given information for each colour. For example, for violet, we have
 d \sin \theta_1 = m \lambda
 d \sin \theta_2 = (m+1) \lambda
By solving two equations for the two unknowns (\lambda\text{ and }m) you can get both the wavelengths and the order.
I have already used that for all the colours. but have no idea what I'm doing wrong if anyone can tell me which colours to look at (to focus on the ones I need) it would save me from going through all this hassle.
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cflau_
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(Original post by pointer15)
I have already used that for all the colours. but have no idea what I'm doing wrong if anyone can tell me which colours to look at (to focus on the ones I need) it would save me from going through all this hassle.
If you know which colours have longer wavelength, you could just calculate two \lambdas. I believe yellow has the longest wavelength and violet has the shortest wavelength, so you can only calculate the wavelengths of the other two colours to find b,c.
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pointer15
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(Original post by cflau_)
If you know which colours have longer wavelength, you could just calculate two \lambdas. I believe yellow has the longest wavelength and violet has the shortest wavelength, so you can only calculate the wavelengths of the other two colours to find b,c.
ok thanks a lot, I've done the questions now but the second longest wavelength happened to be yellow
that's were I got confused
Last edited by pointer15; 1 month ago
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