For the zeroth-order maximum, the light wave coming through the middle slit travels in a straight line to the screen, for convenience-sake we'll say it takes a whole number of wavelengths to get there.
Now at the slit one lower than the middle the laser is diffracted again, one specific wave travels with a path difference equal to one wavelength.
This means that the meet at the mid point at the exact same point in their wave-cycle and interfere constructively making a bright maximum.
If you move a short distance above the zeroth maximum however the the two waves from the two slits that go to that point have waves that interfere destructively and it is dark.
My question is this:
//What would happen if you made the slit separation larger?//
Would there no longer be a zeroth maximum?
Because the wave that goes straight there will still take a whole number of wavelengths to get there, for it nothing has changed. But for the waves the originate from the slits either side of it the distance has just increased, so the waves now no longer interfere constructively and there is no zeroth maximum?
OR
Would the zeroth maximum stay there except it no longer has a wave that originates from the middle slit?
Will the slits either side of it still have the a path difference that is a whole number of wavelengths so they still interfere constructively?
Any and all help is greatly appreciated, thank-you.