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Chapter 38Serway & Beichner 6th Ed.
Fig 38-4a, p.1207
DiffractionDiffraction
D = a
P
wave front
Phasor Model
)()( 110 NEEEE NT
sin
2d
trkAE sinWhere we assume:
sin2
2
)2sin(
2
)2sin(
2
a
II
E
oT
T
E
Note: β = and ER = Eθ
)()( 110 NEEEE NT
These produces the sameinterference patterns!
a
b
D
22.1~
Diffraction from Circular Aperture
02
8II sad
Single Slit Double Slit
Diffraction and Interference
a d
1 0.5 0 0.5 1y
0
0.2
0.4
0.6
0.8
1
langiS
Single Slit Diffraction vs Aperature Size
y/y o
x
= .633 ma = 5.0 ma = 2.5 m
2
0 2/
2sin
yy
sin
2 a
1 0.5 0 0.5 1y
0
0.2
0.4
0.6
0.8
1
langiS
Single Slit Diffraction vs Wavelength
Diffraction also depends on wavelength!
a = 2.5 m
x
y/y o
2
0 2/
2sin
yy
sin
2 a
-0.4 -0.2 0 0.2 0.4y
0
1
2
3
4langiS
Double Slit ; 0.633 m; a2.5 m;d5 m
-0.4 -0.2 0 0.2 0.4y
0
1
2
3
4
langiS
Double Slit ; 0.633 m; a2.5 m;d10 m
MissingPeaks!!
Diffraction Modifies the Interference Pattern!!
-0.4 -0.2 0 0.2 0.4y
0
100
200
300
400
500
600
langiS
N Slits ; 0.633 m; a2.5 m;d5 m; N5
-0.4 -0.2 0 0.2 0.4y
0
200
400
600
800
1000
1200
langiS
N Slits ; 0.633 m; a2.5 m;d5 m; N6
-0.4 -0.2 0 0.2 0.4y
0
2107
4107
6107
8107
langiS
N Slits ; 0.633 m; a2.5 m;d5 m; N8
Primary
Fig 38-29, p.1226
Polarization: Defined as the direction of E-field!
Linear, Circular, Elliptical
Fig 38-28, p.1225
Circular Polarization
Elliptical Polarization
Polarizers
Fig 38-32, p.1228
Fig 38-33, p.1229
Fig 38-34, p.1229