I am to calculated the wavelength of the laser I shone through different slit patterns to create diffraction patters on a screen.
For the single slit diffraction,
xm is the distance from the central image to the mth minimum.
The distance L from the grating to the screen is 1.865
The slit width a is 0.00016
Equation for minima for a single slit system
The Attempt at a Solution
I graphed sinø verses m; in other words:
sinø = (y/a)m
So the slope of that graph is y/a.
So the slope times a is y.
[[ I calculated sinø using (xm)/( ((xm^2)+(L^2))^(1/2) ) ]]
The slope, I found using Excel, of the graph of sinø vs m, is 0.003.
So lambda, y, should be
y = 0.003*0.00016 = 4.8*10^-7
This is a wavelength of 480nm.
The literature value is close to 640nm.
My results for the double-slit is even more off, giving me a calculated wavelength of 2000nm - which is obviously wrong because I wouldn't have been able to see that.
What am I doing wrong?