Question

In YDSE will there be any change in interference pattern if we use 3 slits instead of 2 if yes please explain?

Answer 1

This is actually a very good question, and the experiment has been done. One of the key points of quantum mechanics is Born’s rule that predicts that quantum interference occurs from pairs of paths. However, there is no logical reason preventing multi path interference, i.e. higher order interference where three or more paths would have coincidental regions of amplitude reinforcement, and that would falsify the standard version of quantum mechanics. So, congratulate yourself; you have thought up a critical test for one of the more successful theories in physics. However, you do not overturn quantum mechanics. The experiment showed that there was no multi-order interference to within a factor of 10^-2. All bands you see are the result of two waves reinforcing at that point (but they do not have to be the same two waves. All three waves interfere, but they give bands due to two-wave reinforcement, with all combinations of the possible waves.) Accordingly, quantum mechanics as you know it remains unchanged.