Hello /sci/ I was in physics lecture (waves and optics) and I asked the professor if the intensity maximum of slit experiment light increases if the number of slits increases.
At first he thought they did not and the intensity remained the same, but then I talked to him again after class and expressed how I thought the intensity would increase as a function of the integral.
Online MIT and Georgia Tech lecture notes always show the maximum intensity as one as the attached image shows. Is this correct? I think the intensity would increase as the interference decreased. Where is that energy going?
Thanks!
Total area is conserved so peak heights must increase.
>>7968952
That is what I was thinking, could you explain why the area must be conserved?
Also why does MIT and Georgia Tech both have it wrong? I guess NYU as well because the professor did it wrong at first.
>>7968949
as the number of slits increase, the distance between each slit decreases (we want to keep the original area that light strikes the same to ensure we are always talking about the same incoming energy). We know that for diffraction gratings, m=d/lambda where 2m+1=max number of bright spots. Since d decreases, m also decreases and the total intensity f course stays the same. So it seems you're correct that the more slits a grating has the higher the intensity of each spot.
>>7968957
Tue total area is related to the total energy.
And they don't have it wrong. They don't label the y axis in those figures. They are arbitrary.
>>7968949
Remember that in the double slit experiment, the pattern is the result of adding thousands of consecutive "clicks." Intensity is not very well defined in such a case; what matters is the ratio of one peak's height to another's. The graphs like the one you have there are drawn with the vertical axis in arbitrary units--the curve can be normalized to integrate to 1, representing the probability density of a each click being at a particular point.
Nonetheless, if your grating is absorbing selectively, than as you add more slits, the rate of "clicks" will go up. Thus, the average "intensity" increases, as well as the relative sharpness of the various peaks.
>>7968972
This isn't the double slit experiment as you are thinking. This is diffraction patterns.
>>7968967
No in MIT and Georgia tech notes they label both with a max of one.
And it isn't really that related to total energy. I started doing the integral. If someone could finish it then it would probably make more sense.
>>7968987
The 1 on the y axis just means [math] I_0 [/math] I bet you the central peak has a value of 1 for both, it just normalizes the entire curve to this "initial" intensity. It doesn't mean both 1's are the same intensity, as intensity changes for each experiment but the shape of the distribution is the same no matter what initial intensity.
>>7968986
Diffraction patterns are the same. Any wave pattern is just a bunch of photons (electrons, etc.) consecutively striking the detector.
>>7968949
a few people say that the born rule is violated in the triple slit experiment
http://arxiv.org/find/all/1/all:+AND+Experiment+AND+Triple+Slit/0/1/0/all/0/1
anyway, here is a short article which calculate the WF
http://arxiv.org/abs/1510.04186
>>7968993
Why would they draw it this way? If intesity increases the plots should show such! Especially since it is supposedly the same set up each time just with more slits
>>7969033
nobody cares about how intensity changes between experiments. The interesting stuff is ow it changes with position.
>>7968949
It's been a long time since I took physics 3, but I swear to god I remember actually doing this in class, where the professor showed the maxima did increase in intensity, yet the overall intensity across the screen remains constant.
