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Fu-Kwun Hwang
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« on: January 29, 2004, 09:46:55 PM » |
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Registed user can get files related to this applet for offline access.If java program did not show up, please download and install latest Java RUN TIMEor <center> </center> This java applet shows how the electric field, the magnetic field and the wave vector inter-relate as the electromagnetic wave propagates through space.
| Red arrow | Blue arrow | Green arrow |
| Electric field E | Magnetic field B | Velocity vector of wave V |
| fixed | Click near tip of B then drag the mouse to change the velocity of the EM wave | keep E X B = V (VXE=B) |
Press the start Button to start the animation. The electromagnetic wave propagates in the opposite direction (from the origin). Press the LEFT mouse button to pause the animation. Press it again to resume. Press the RIGHT mouse button and drag the mouse to change the viewing angle. Right click near the origin to move it. T-field is the period (in seconds) [or 'fractions of a second' if referring to less than one second]. The speed of propagation remains constant but the period may vary ...(Thanks to Michael De Groot for his suggestion). Press the Reset button to reset. Thank Mark Servis for correction in the code (Oct. 8, 2001) Your comments/suggestions are highly appreciated. or
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« Reply #1 on: January 30, 2004, 07:40:49 AM » |
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Subject: EM wave Applet Date: Mon, 01 Sep 1997 17:34:13 -0700 From: "Sunil K. David" < davids@cookman.edu> Organization: Bethune-Cookman College To: hwang@phy03.phy.ntnu.edu.tw, rao@cookman.edu Hi: You have made my job quite simple in showing the prop. of EM wave for my class. Congratulations. Great applet. Goodluck, Bye, Sunil K. David, M.Sc., M.Sc. Ph.D. Assistant Professor of Physics |
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« Reply #2 on: January 30, 2004, 11:38:05 AM » |
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Subject: E&M Waves Date: Tue, 09 Mar 1999 00:34:41 -0800 From: Chun-Te Peter Wu < peterw@ucla.edu> To: hwang@phy03.phy.ntnu.edu.tw Hi Professor, I visited the your E&M website and I am very impressed with the animation of the E&M waves. I especially liked the rotations of axis. Good Job -Peter |
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« Reply #4 on: January 30, 2004, 12:53:45 PM » |
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Subject: Electromagnetic wave propogation Date: Thu, 21 Oct 1999 15:45:24 +0100 From: "Arif Zubairi" < zubairi@nortelnetworks.com> To: "'hwang@phy03.phy.ntnu.edu.tw'" < hwang@phy03.phy.ntnu.edu.tw> Hi I was recently scouring the net looking for a suitable picture to demonstrate the orthogonal mode of an electromagnetic wave in an optical fibre for a presentation on polarisation dispersion (my artistic skills are nil). I came across your moving Java applet description of an EM wave and was suitably impressed as its exactly the type of picture I'm looking for. I was wondering whether you might have still pictures of the sort that I might be able to post in a Powerpoint presentation. If you do I would be much obliged. Thanks Regards Arif Zubairi Product Engineering Nortel Networks External: % 0181 945 3720 ESN: % 730 3720 E-mail: ) zubairi@nortelnetworks.com -------------------------------------------------------------------------------- thanks kindly. Much appreciated. |
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« Reply #5 on: January 30, 2004, 05:01:37 PM » |
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Date: Mon, 22 Jan 2001 22:03:52 -0500 From: Katrin Kneipp < KatrinKneipp@compuserve.com> Subject: Your em wave animation Sender: Katrin Kneipp < KatrinKneipp@compuserve.com> To: "H.Wang" < hwang@phy03.phy.ntnu.edu.tw> Dear collesgue, I'm writing to kindlly ask you for setting a link to your em Wave animati= on from the home page of my Single Molecule Spectroscopy course, MIT course 6.975 Spring 2001. http://ourworld.compuserve.com/Homepages/KatrinKneipp/6975.htmMany thanks and best regards, Katrin Kneipp *********************************** Katrin Kneipp Rockefeller Mauze Visiting Professor Massachusetts Institute of Technology Department of Physics Department of Electrical Engineering and Computer Science G. R. Harrison Spectroscopy Laboratory, Room 6-014 77 Massachusetts Avenue, Cambridge MA 02139-4307 Phone (617) 253 3378, Fax (617) 253 4513 e-mail:kneipp@usa.net |
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dolanl
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« Reply #6 on: May 05, 2004, 06:47:20 AM » |
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Mr. Hwang:
In your animated propagation of EM waves, what is the green dot?
electrons have charge
photons have discrete enery which do not vary during propagation
light waves are compsed of photons(not electrons or positrons)
photons travel in straight lines
Are your graphics about electon emision?
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Fu-Kwun Hwang
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« Reply #7 on: May 06, 2004, 07:30:23 AM » |
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It could represent an oscillating charge (if this is the case: the simulation only show one of the possible EM-wave)
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« Reply #8 on: May 06, 2004, 11:51:26 PM » |
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using a length of open-circuited transmission line, we can design a tuning stub to match a 75ohm line to (150-j75)ohm load.
What is the distance from the load to place the line, and legth of open circuited line. Do you know any method to solve this, other than smith's chart?
of what practical relevance is the design of matching stubs? what factors would dictate your selection of an open-circuited vs short-circuited?
Thanks, spectnas
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« Reply #9 on: July 24, 2004, 03:42:48 PM » |
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Topics containing links to people's sites are unneeded and contribute nothing as a whole, much like topics containing content like this one. You could have PMed a moderator and asked this same question and received the same Blackjack Rules response. Please do so in the future. |
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« Reply #10 on: August 16, 2004, 04:14:27 PM » |
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what kind of sport is this? i ve never heard about it and never seen it... I like - football, tennis, Refinancing Mortgage figure skating, extreme sports Dislike - hockey, basketball, car racing, box and all the rest |
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« Reply #11 on: September 15, 2004, 04:13:37 AM » |
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[b:63c7c331eb]Beautiful![/b:63c7c331eb]
:shock: What a beautiful animation. To those who are curretly studying Electromagnetic Waves - like Í'm doing - this is a spetacular way of seeing how those fields propagates with a beam of light!
VF
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Fu-Kwun Hwang
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« Reply #12 on: July 20, 2005, 10:44:15 AM » |
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David Paraschuk :
> Hello,
>
> I was just running though some of your excellent java applets and I have a question concerning the propagation of EM waves. Every text resource or web resource depicts the E and B field components as reaching a maximum and minimum in phase. Yet the theory of Maxwell clearly indicates that the rate of field change in the mutual self-induction cycle is what is important, ( E∝ £GB/£Gt ). I think during the wave cycle when the E field is a maximum, the rate of change temporarily falls to zero and the the B field at that instant would be zero. The opposite would be true for the generation of the E field by a changing B field. Therefore a maximum E and B field can never be produced together in time and space.
>
> If this follows then the traditional drawings of the EM waves are incorrect and the wave peaks should be out of phase by 180 degrees!
>
> If you could briefly comment on this thinking I would be in your debt. Thank you.
It is the gradient of E in the space coordinate is proportion the rate of change in B field.
i.e. grad E = - dB/dt
It is different from E= -dB/dt (E and B should be out of phace)
So E and B do not necessary to be out of phase. They can be in phase or out of phase or other case (phase different not 90 degree).
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jashua
student
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« Reply #13 on: January 14, 2006, 06:07:57 AM » |
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shouldnt it be B X V = E instead of V X B = E ??
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Fu-Kwun Hwang
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« Reply #14 on: January 14, 2006, 04:19:57 PM » |
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Sorry! It is corrected. It should be EXB=V or VXE =B or BXV=E ! :-)
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Helder de F. e Paula
Physics teacher in Brasil, South America
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« Reply #15 on: March 02, 2006, 05:03:09 AM » |
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I want to get file related to EM Waves for offline use in my classroom.
Thank you.
Helder de F. e Paula
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Fu-Kwun Hwang
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« Reply #16 on: March 02, 2006, 08:52:26 AM » |
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Login to the forum and press "GET APPLET FILES" button near the end of the first message.
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sunilbalani
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« Reply #17 on: August 26, 2006, 01:46:15 PM » |
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great job thanks for making physics so understandable to students.it really helps if we can show them what really happens then talking about what happens. congratulations. great combination of physics and programming.
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ferro638
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« Reply #18 on: May 07, 2007, 01:42:14 AM » |
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Hello!
Excellent animation! I'm doing a PowerPoint presentation about this subject. Is it possible to put this animation in my PoerPoint presentation, to be shown in a computer WITHOUT internet? If so, how can I do it?
Thanks.
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Fu-Kwun Hwang
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« Reply #19 on: May 07, 2007, 11:38:00 PM » |
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As far as I know, java applets can not be embed into powerpoint.
However, you can download out applet and add a link in powerpoint to open the web page which contains java applets.
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NightAngel
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« Reply #20 on: July 05, 2007, 12:18:29 AM » |
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hihi... can i have the source code? i was download the file, it is appear in .class file. is it possible view in source code from the .class file?
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Fu-Kwun Hwang
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« Reply #21 on: July 10, 2007, 04:58:16 AM » |
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You should have received source code now.
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kontellis
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« Reply #22 on: February 06, 2008, 06:04:11 PM » |
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Hello Mr Huang and the rest of your team. Congratulations for the great job you make. I'm Kontellis George a teacher of Physics at 3rd Lyceum of Mytilini Greece. I must thank you for the exciting Applets you have. Many topics of my teachings are much easier to teach with them. I have two questions about EM waves. 1. When EM waves transport inside an object is E/B equal with 300000000m/s or smaller? 2. Near the antenna the two fields seem to have a phase difference of 90 but at a long distance their phase difference become zero. Why is that? Thank you George Kontellis kontellis@sch.gr |
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Fu-Kwun Hwang
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« Reply #23 on: February 06, 2008, 11:33:53 PM » |
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1. E/B is the speed of the EM wave and the speed of EM wave is near c=3*108m/s in vacuum.
But the speed is reduced to c/n when in an object, where n is the refraction index for that EM wave.
2. Could you explain why there is a 90 degree difference in phase for E/M wave near the antenna?
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