### Author Topic: Reflection and Refraction  (Read 641917 times)

#### Fu-Kwun Hwang

• Hero Member
• Posts: 3062
##### Reflection and Refraction
« on: January 29, 2004, 06:55:50 pm »
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The Transmission of Wave through Dense media -- Reflection and Refraction

The Huygensâ€“Fresnel principle:It recognizes that each point of an advancing wave front is in fact the center of a fresh disturbance and the source of a new train of waves; and that the advancing wave as a whole may be regarded as the sum of all the secondary waves arising from points in the medium already traversed.

How to play:

1. The whole area has been divided into two region (Top/Buttom).

1. Click within the black semi-circular near the top , then drag the mouse (Left-Right) to change the angle of incidence.

2. You can enter the ratio of index of refraction for those two media (n2/n1).

3. Click Faster/ Slower to change the wave speed.

4. Suspend/Resume the animation.

1. The animation is suspended when you press down the left mouse button, it is resumed when you released the mouse button.

2. If you press the right mouse button, the animation is also suspended. But you will have to press the right mouse button again to resume the animation.

3. What if I press the right mouse button first then press the left mouse button ? Try it!

* For sound wave originates in and impings on water:

If the incident angle is larger than critical angle (about 13 degree),

the sound wave will be total reflected. No sound will be transmitted.

When a beam of light impings at some angle on the smooth flat surface of an optically dense medium, the wave "sees" a vast array of very closely spaced atoms that will somehow scatter it.
(At the wavelengths of light -- d=500nm -- the Earch's atmosphere at STP has about 106 molecules in such a d3-cube).
As the wavefront descends, it excites one scatterer after another, each of which reradiates a stream of photons that can be thought of as a hemispherical wavelet in the incident medium.
Because the wavelength is so much greater than the separation between the molecules, the wavelets advance together and add constructively in only one directions, and there is one well-defined reflected beam.
The wavelets bend as they cross the boundary, because of the speed change.
For similar reason, they form one well-defined refracted beam.

Ratio of index of refraction n2/n1 = v1/v2, where v1, v2 are speed of wave in media 1 and 2.
For light (electromagnetic wave):

 substances Air Water Plexglass Diamond indices of refraction 1.00029 1.333 1.51 2.417

For sound wave :

 material Air water vapor fresh water sea water Aluminum speed of sound (m/s) 331 401 1493 1513 5104

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• Guest
##### topic16
« Reply #1 on: January 30, 2004, 12:22:10 pm »
Subject: fed.cuhk.edu.hk/sci_lab/ntnujava/propagation/propagation.html
Date: Tue, 10 Nov 1998 23:00:38 -0500
From: "Mark C. Barnett" <mcbarnet@indiana.edu>
To: <hwang@phy03.phy.ntnu.edu.tw>
fantastic web page. i'm doing a report on wave division multiplexing and
found your web site very useful and easy to use. thanks for the help.

mark

• Guest
##### topic16
« Reply #2 on: March 30, 2004, 04:11:40 am »
I'm lazy and want to have this post on the top... so I am posting. Aren't I smrt?

#### Pilimala

• student
• Newbie
• Posts: 1
##### topic16
« Reply #3 on: April 01, 2004, 05:30:45 pm »
Why the speed of sound is faster in Aluminium? Is it related to the density of a material? :shock:

#### Calistes

• Newbie
• Posts: 2
##### Re: Reflection and Refraction
« Reply #4 on: November 15, 2004, 08:43:27 pm »
This is really fantastic, I have a suggestion.I think if the path of the wave (directions) are not indicated by the colours,it would have been better. But still you know better.

#### fee

• Newbie
• Posts: 2
##### Huygens' Principle Applet
« Reply #5 on: August 28, 2005, 06:47:54 pm »
This is a very nice Applet. Thank you.
Can I use it for my students? Where was it taken from?

#### Fu-Kwun Hwang

• Hero Member
• Posts: 3062
##### topic16
« Reply #6 on: August 29, 2005, 11:01:21 am »
You will find a button labeled "GET APPLETS FILES" near the end of the first message (if you are a registered user and login to the system).
Just click that button and files related to this applet will be packed and send to your email account.

Fu-Kwun :-)

#### Lucciano

• Systems Analist
• Newbie
• Posts: 1
• eletronics , logicel tools,eg.: mathlab
##### topic16
« Reply #7 on: September 30, 2005, 12:03:52 am »
Please help us to receive thouse applets class files , just because theres no GET APPLETS FILES button available, tks .This is an lovely work , excelent job .Congratulations for this.

#### shahabpk

• Newbie
• Posts: 2
##### I want the source code of this applet
« Reply #8 on: November 03, 2005, 08:35:16 am »
I want the source code of this applet

#### Fu-Kwun Hwang

• Hero Member
• Posts: 3062
##### topic16
« Reply #9 on: November 03, 2005, 04:40:59 pm »
You need to login to find the "GET APPLET FILE" button!

#### santa_thanapol

• student
• Newbie
• Posts: 1
##### topic16
« Reply #10 on: November 11, 2005, 01:37:54 pm »
You need to login to find the "GET APPLET FILE" button!

#### Petr

• Newbie
• Posts: 1
##### Very nice
« Reply #11 on: April 08, 2006, 05:54:25 pm »
I like it very much.

Is there a chance to change an area between this two xxxions. Thanks to black points and mouse for example - I like circle etc.

If there is a chance to get the source file, not only the class, then i will try it by myself.

Thanks for answer on my email.

#### green8003

• Newbie
• Posts: 4
##### topic16
« Reply #12 on: May 01, 2006, 12:06:53 am »
hi
im glad to watch these simulations.But i have a question.why i dont watch all of simulations.only afew simulations i can see.i dont suppose that from me.because some simulations when i click them i see but others i didnt.

if u express me this i will be happy.

thanks...

#### Fu-Kwun Hwang

• Hero Member
• Posts: 3062
##### topic16
« Reply #13 on: May 01, 2006, 12:35:22 pm »
There are two categories: Simulationsunder Physics simulation (current one) are created by JDK1.0.2 almost 10 years ago. Most browser should be able to support it.

For those simulations under "Easy Java simuations (EJS)" are created with EJS and need latest java installed. You need JDK1.5 and above. You need to download and install latest JRE (Java Run time Environment)

• Newbie
• Posts: 1