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# Questions about the double slit experiment Tweet

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1. Questions about the double slit experiment
Firstly when you position your laser - Do you position it so that it is aimed at the midpoint between the two slits?
If so what happens if you move the laser from this midpoint so that its closer to one of the slits than the other
Also what happens to the interference pattern you see if you move the slits further apart?
And finally what would you see if you had two identical lasers and positioned one firing directly through one slit and the other directly through the other - What would happen to the interference pattern?

Thanks
2. Re: Questions about the double slit experiment
The laser is ideally wider than the two slits, so that photons are fired randomly within that beam space.

If the laser doesn't encompass one of the slits then no(very few) photons will go through it.

I feel like that kind of invalidates the first 3 questions.

As for the fourth, both lasers are firing fairly randomly within the space of their laser, so the chance of two photons actually having any impact on each other is very low. Likely you would just get two similar interference patterns of both sides of the slits.
3. Re: Questions about the double slit experiment

this video is good to visualze it
4. In answer to the third question, increasing the distance between the two slits, or the slit separation, would decrease the fringe separation in the interference pattern, so the pattern would be narrower.

This also happens if you decrease the width of the slits themselves, as there is less diffraction so the fringes are more narrowly spaced. The fringes will also be darker as less light can get through the slits.

For the fourth question, I believe you'd just get two identical single-slit diffraction patterns (assuming the slits were identical and the light sources coherent).

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