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cheff3r
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Homework Statement
A line corresponding to light of the wavelength 519.8 nm is observed at an angle 12 degrees in the second-order spectrum of a diffraction grating. The grating is 1 cm in width,
what is the line spacing of the grating?
how many per centimetre?
what is the lowest order in which the grating can resolve both this line at 519.8 nm and a near by line at 520 nm?
If these lines were to be resolved in the first-order diffraction pattern, what width would the grating need to be made?
If the grating is illuminated by light (400-700nm) what is the largest order for which complete spectrum of visible light can be observed?
Homework Equations
m*[tex]\lambda[/tex]=d*
where m is the 'order'
The Attempt at a Solution
So I don't really now what I'm doing yet, but I want only help on the first couple parts then when I get them right possible help in the later sections
so for the first question
d= [tex]\frac{m*lambda}{sin (theta)}[/tex] = [tex]\frac{2*519.8*10^-9}{sin 12}[/tex] = 5*10^-6 m
so does this represent spacing between each diffraction? if this is the case then the next part is 5*10^-4 per centimetre??
Either way what the next part is not really related so I will attempt it as well (what is the lowest order in which the grating can resolve both this line at 519.8 nm and a near by line at 520 nm?)
so i used the formula twice
m*[tex]\lambda[/tex]=d*sin [tex]\theta[/tex]
once for each wave length ([tex]\lambda[/tex]) and the plane was to solve it for different m's until it gave the same d, however I'm unsure what to do with the sine term can i drop it? (since we are not considering an angle)
Yeah so I am likely to be completely wrong with this (especially the last bit I tried) but I did a decent attempt the problem,
Has anyone one got a decent website for teaching this topic? (I can't find one)