Why the central fringe is brighter in the double slit experiment

[jaumzaum]

Why the central fringe in the double slit experiment is brighter than the others? I've tried but I still cannot undersand this.
Can someone try to explain it to me. I don't know too much in modern physics, please be patient :)
thanks for any help

 

[jtbell]

Why would you expect it not to be the brightest?

(This is not meant to be a snarky response. I simply think it would be helpful to know if you have any specific thoughts about this so that people can address them directly instead of having to guess.)

 

[Maui]

When most of the particles land in the center, why would anyone wonder why the central fringle is the brightest?

 

[jaumzaum]

Why would you expect it not to be the brightest?

(This is not meant to be a snarky response. I simply think it would be helpful to know if you have any specific thoughts about this so that people can address them directly instead of having to guess.)

I would say they will all be the same bright. I really don't know what contributes for a fringe to be brighter than the other. all fringes have the same phase diference, for me they sould all be the same bright. sorry for my ignorance :(

 

[jtbell]

In general, what you see is a combination of the effects of single-slit diffraction from the individual slits, and double-slit interference between the two slits. See here:

http://hyperphysics.phy-astr.gsu.edu/hbase/phyopt/mulslid.html

and compare the "single slit diffraction" and "double slit diffraction" pictures. Also see here:

http://hyperphysics.phy-astr.gsu.edu/hbase/phyopt/dslit.html