DIFFRACTION-:

 

1)it occurs due to superpos. of secendary wavelets frm exposed part of a coharent source

2)inte3nsity of succesive bright fringes goes on dec.

3)intensity of dark fringes is never zero

4)diff. fringes are never of = width

 

5)conditions for max. are

 

a)path diff. delta.x= (2n+1)lamda/2

b)phase diff.         = (2n+1)lamda/2

c)time diff.            = (2n+1)T/2

 

6)conditions for minima are  

 

a) path diff. = n*lamda

b)phase diff.= 2n*pi

c)time diff.   =nT