what is heat

6 answers

LOL - first do the diffraction video :)
i did and i still don't understand
You watched that double slit video and do not understand what diffraction is?

Maybe look up "Huygen's Principle"
I will try.
Yes, I bet this will help:

http://physics.about.com/od/mathematicsofwaves/a/huygensprincipl.htm
more
http://physics.about.com/od/mathematicsofwaves/a/interference.htm
http://www.acoustics.salford.ac.uk/feschools/waves/diffract3.php