1 24 overview wave effects: interference, diffraction polarization, scattering homework: 1, 12, 43,...
TRANSCRIPT
![Page 1: 1 24 Overview wave effects: interference, diffraction polarization, scattering Homework: 1, 12, 43, 57, 67](https://reader034.vdocument.in/reader034/viewer/2022051000/56649c9d5503460f9495c21f/html5/thumbnails/1.jpg)
1
24 Overview
• wave effects:
• interference, diffraction
• polarization, scattering
• Homework:
• 1, 12, 43, 57, 67.
![Page 2: 1 24 Overview wave effects: interference, diffraction polarization, scattering Homework: 1, 12, 43, 57, 67](https://reader034.vdocument.in/reader034/viewer/2022051000/56649c9d5503460f9495c21f/html5/thumbnails/2.jpg)
2
waves• pass through another wave undisturbed
• diffract video demo simulation
• Reflect wave tank demo
![Page 3: 1 24 Overview wave effects: interference, diffraction polarization, scattering Homework: 1, 12, 43, 57, 67](https://reader034.vdocument.in/reader034/viewer/2022051000/56649c9d5503460f9495c21f/html5/thumbnails/3.jpg)
3
Interference
• amplitude change due to adding waves
• correlation (Coherence) - required for strong interference effects
• misalignment of waves (phase) is zero for constructive (bright)
• 180 deg: destructive (dark)
• Wave tank demo
![Page 4: 1 24 Overview wave effects: interference, diffraction polarization, scattering Homework: 1, 12, 43, 57, 67](https://reader034.vdocument.in/reader034/viewer/2022051000/56649c9d5503460f9495c21f/html5/thumbnails/4.jpg)
4
double-slit experiment• coherent light
• Interference pattern
• path difference
![Page 5: 1 24 Overview wave effects: interference, diffraction polarization, scattering Homework: 1, 12, 43, 57, 67](https://reader034.vdocument.in/reader034/viewer/2022051000/56649c9d5503460f9495c21f/html5/thumbnails/5.jpg)
5
central max
m = 1 bright fringe
m = 2 bright fringe
m = 1 dark fringem = 2 dark fringem = 3 dark fringe
L
naming convention
![Page 6: 1 24 Overview wave effects: interference, diffraction polarization, scattering Homework: 1, 12, 43, 57, 67](https://reader034.vdocument.in/reader034/viewer/2022051000/56649c9d5503460f9495c21f/html5/thumbnails/6.jpg)
6
Double-Slit Phase Difference
• Bright: (dsin) = 0, 1, 2, … wavelengths
• Dark: (dsin)= ½, 1½, 2½, … wavelengths
3,... 2, 1, m sin Bright md
3,... 2, 1, m )(sinDark 21 md
![Page 7: 1 24 Overview wave effects: interference, diffraction polarization, scattering Homework: 1, 12, 43, 57, 67](https://reader034.vdocument.in/reader034/viewer/2022051000/56649c9d5503460f9495c21f/html5/thumbnails/7.jpg)
7
Single Slit Pattern
![Page 8: 1 24 Overview wave effects: interference, diffraction polarization, scattering Homework: 1, 12, 43, 57, 67](https://reader034.vdocument.in/reader034/viewer/2022051000/56649c9d5503460f9495c21f/html5/thumbnails/8.jpg)
8
![Page 9: 1 24 Overview wave effects: interference, diffraction polarization, scattering Homework: 1, 12, 43, 57, 67](https://reader034.vdocument.in/reader034/viewer/2022051000/56649c9d5503460f9495c21f/html5/thumbnails/9.jpg)
9
Polarizing Filters• Polarizing material
allows the passage of only one direction of E
• Malus’ Law:
20 cosI I
![Page 10: 1 24 Overview wave effects: interference, diffraction polarization, scattering Homework: 1, 12, 43, 57, 67](https://reader034.vdocument.in/reader034/viewer/2022051000/56649c9d5503460f9495c21f/html5/thumbnails/10.jpg)
10
Two Filters (incident light unpolarized)
• 1st reduces intensity by 1/2.
• 2nd reduces according to Malus’ Law
![Page 11: 1 24 Overview wave effects: interference, diffraction polarization, scattering Homework: 1, 12, 43, 57, 67](https://reader034.vdocument.in/reader034/viewer/2022051000/56649c9d5503460f9495c21f/html5/thumbnails/11.jpg)
11
Polarization by Scattering and Reflection
• Light scattered at 90 degrees is 100% polarized.
![Page 12: 1 24 Overview wave effects: interference, diffraction polarization, scattering Homework: 1, 12, 43, 57, 67](https://reader034.vdocument.in/reader034/viewer/2022051000/56649c9d5503460f9495c21f/html5/thumbnails/12.jpg)
12
Summary
• all waves diffract & interfere
• coherence required for strong effect
• path difference determines interference for double-slits and thin-films
• light polarization & polarizing filters
![Page 13: 1 24 Overview wave effects: interference, diffraction polarization, scattering Homework: 1, 12, 43, 57, 67](https://reader034.vdocument.in/reader034/viewer/2022051000/56649c9d5503460f9495c21f/html5/thumbnails/13.jpg)
13
thin-film interference• causes certain colors to become more or
less intense.
• Ex. oil on water, soap bubble, coatings
• 1+2 constructive or destructive
![Page 14: 1 24 Overview wave effects: interference, diffraction polarization, scattering Homework: 1, 12, 43, 57, 67](https://reader034.vdocument.in/reader034/viewer/2022051000/56649c9d5503460f9495c21f/html5/thumbnails/14.jpg)
14
Reflection phase• off higher index: ½ wavelength phase
change (Ex. ray 1 in diagram)
• off lower index: 0 (Ex. ray 2 in diagram)
![Page 15: 1 24 Overview wave effects: interference, diffraction polarization, scattering Homework: 1, 12, 43, 57, 67](https://reader034.vdocument.in/reader034/viewer/2022051000/56649c9d5503460f9495c21f/html5/thumbnails/15.jpg)
15
Thin Film Problem Solving
Dark
Bright
,2 ,1 ,
3, 2, 1, *)or (0
2
21
21
212
1
film
t
* 0: no reflection phase changes (or two)
* ½: one reflection phase change
![Page 16: 1 24 Overview wave effects: interference, diffraction polarization, scattering Homework: 1, 12, 43, 57, 67](https://reader034.vdocument.in/reader034/viewer/2022051000/56649c9d5503460f9495c21f/html5/thumbnails/16.jpg)
16
Ex. t = 100nm. Light wavelength = 400nm in water.
400
)100(2 )or (0
221
21
nm
nmt
film
Ray 1 has reflection phase change, Ray 2 does not. (= ½)
1 21
21 Bright
![Page 17: 1 24 Overview wave effects: interference, diffraction polarization, scattering Homework: 1, 12, 43, 57, 67](https://reader034.vdocument.in/reader034/viewer/2022051000/56649c9d5503460f9495c21f/html5/thumbnails/17.jpg)
17
diffraction grating
• N = #lines/cm,
• Spacing: d = 1/N
• Video demo
Bright 21 0 sin , ..., , n nd
![Page 18: 1 24 Overview wave effects: interference, diffraction polarization, scattering Homework: 1, 12, 43, 57, 67](https://reader034.vdocument.in/reader034/viewer/2022051000/56649c9d5503460f9495c21f/html5/thumbnails/18.jpg)
18
a = Slit-Width
(a ≠ d)
Single Slit Diffraction
![Page 19: 1 24 Overview wave effects: interference, diffraction polarization, scattering Homework: 1, 12, 43, 57, 67](https://reader034.vdocument.in/reader034/viewer/2022051000/56649c9d5503460f9495c21f/html5/thumbnails/19.jpg)
19
waves• pass through another wave undisturbed
• diffract video demo
• Refract and reflect