13.4 Double slit interference

1
13.4 Double slit interference
2
From one source and two gaps
1st bright fringe
central fringe
1st bright fringe
3
From one source and two gaps
1st bright fringe
central fringe
1st bright fringe
- the closer the slits become the wider the
fringe separation.
- waves of short wavelength give narrow fringe
separation because blue light diffracts less.
4
(No Transcript)
5
Path difference
Phase difference
6
Path difference
Phase difference
7
Double Slit interference - theory
screen
First bright fringe
W
Central fringe
8
Double Slit interference - theory
D
screen
First bright fringe
W
?
Central fringe
wavelength
600nm D slit to screen distance
2m S slit separation
0.5 mm W fringe width
1mm
9
For constructive interference at the screen ( ie
a bright fringe )
Wave fronts from S1 and S2 must arrive at the
screen in phase with a path difference of a
whole number of wavelengths
10
For constructive interference at the screen ( ie
a bright fringe )
Wave fronts from S1 and S2 must arrive at the
screen in phase with a path difference of a
whole number of wavelengths
For destructive interference at the screen ( ie
a dark fringe )
Wave fronts from S1 and S2 must arrive out of
phase with a path difference of half a
wavelength
11
soh cah toa
12
soh cah toa
13
soh cah toa
14
soh cah toa
15
(No Transcript)