Physics - Diffraction of Waves 発表
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🌊 "Diffraction" of Waves
🔍 Examples
https://gyazo.com/0697c949205407e478433c32b13f069f https://gyazo.com/d93991875b4e4971fc97b1e7bf72bfac
https://gyazo.com/4cfd5008411e858fa9cf3813fdce96dc
https://kognity-prod.imgix.net/media/edusys_2/content_uploads/4.4.3.4.a8c1274135095257f8c3.png?w=825&auto=compress
📚 Prerequired Knowledges
Wave front
Blue line: "Wave front"
Red arrow: "Rays"
https://d3vrb2m3yrmyfi.cloudfront.net/media/edusys_2/content_uploads/4.3.1.6a.ccd386de4e763288248b.gif
https://gyazo.com/dcdb0ae3b657a45ee0852fc1acd45f79
Simulation
https://www.compadre.org/osp/EJSS/4480/268.htm
🤔 Huygen's Wave Theory
https://kognity-prod.imgix.net/media/edusys_2/content_uploads/4.4.3.2.ba42a10b65abe4633c43.png?w=900&auto=compress
Proposes a new way to understand the movement of wave
Think that every points on a wavefront are wave sources
https://kognity-prod.imgix.net/media/edusys_2/content_uploads/4.4.3.3.db6ba110f2d2d7beb5c5.png?w=825&auto=compress
https://gyazo.com/de39e493d2e741fc4c70a225e659a5e3
These movements can be explained by the theory
Now more mathematical? part
https://gyazo.com/0697c949205407e478433c32b13f069f https://gyazo.com/d93991875b4e4971fc97b1e7bf72bfac
Q. How does wavelength $ \lambdaand opening of obstacle$ waffect the diffraction?
Q. How does wavelength $ \lambdaand opening of obstacle$ waffect the diffraction?
Diffraction effect is significant when $ \frac{\lambda}{w}>1
i.e. When wavelength is comparable or larger than opening
Generally, diffraction is larger when: lambda is larger than opening
💪 Some questions
Q. Why can we hear, but can not see the source behind the wall?
A.
wavelength of audible sound: 17mm - 17m
wavelength of visible light: 360nm - 400nm
wave length of visible light is much smaller than opening
--> Almost no diffraction of light
Q.
https://gyazo.com/62b0f6dd20216ab13f4dadb3e780d401
Hint: Use $ c=f\lambda
A.
https://gyazo.com/5990097e4b1ff18eaff041c8b426e0e1
Q. Draw the wavefronts of these waves as they emerge through the aperture.
waves of wavelength 1mm approaching an aperture of size 8mm
waves of wavelength 1mm approaching an aperture of size 1mm
A.
https://gyazo.com/79aad6fd64f84b3e105bc643dbecd9db
https://gyazo.com/8bf2a8828d41f86f5a9735fa82563bdc