NTNUJAVA Virtual Physics Laboratory
Physics Simulations to help you enjoy the fun of physics!
February 10, 2010, 04:53:31 AM *
Welcome, Guest. Please login or register.
Did you miss your activation email?

Login with username, password and session length
News: This site host hundreds of physics related java simulations under create common license. All registered user will be able to get files for offline use when user login and view the simulation. Switch to this new system on 2007/02/14. (previous system2001-2007, 1996-2001) ,Check out Chinese forum to find more simulations and resources in Chinese.
 
   Home   Help Search Login Register  
"Make priority, take action and start now." ...Wisdom
Google Bookmarks Yahoo My Web MSN Live Netscape Del.icio.us FURL Stumble Upon Delirious Ask FaceBook

NTNUJAVA Virtual Physics Laboratory
Physics Simulations to help you enjoy the fun of physics!  > JDK1.0.2 simulations (1996-2001) > Optics > Find the fastest Path
Pages: [1]   Go Down
« previous next »
  Print  
Author Topic: Find the fastest Path  (Read 64496 times)
0 Members and 1 Guest are viewing this topic. Click to toggle author information(expand message area).
Fu-Kwun Hwang
Administrator
Hero Member
*****
Offline Offline

Posts: 1966


WWW
« on: January 29, 2004, 10:47:02 PM »
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 TIME
There are 2 translations,
Higher number at the end means more translation been done.
or



In the above java applet, there are two different regions (green and yellow).
    The condition is :
      An object (red) located at the top left corner of the green region.
      It is going to move to the bottom right corner of the yellow region.

    Due to different friction in these two regions,
      its speed is also different (green: V1 , yellow: V2)You can change value of V1 and V2 from the textfield.

How to chose a path such that minimizes the travel time?
    Those two arrors represent the velocity vectors at those two region.
    You can click the left mouse button at the tip of the velocity vector
      and drag it left and right, to change the traveling path.

    To make it more interested. You can click the mouse button at the boundary,
      and drag it up and down, to change the height of those two regions.

    Press Start button to start the animation.
      A red ball will move along the chosed path.Another ball(blue) will follow the fastest path if you click the show checkbox:

    When it stop, compare the ratio of L1/L2 and compare with V1/V2Did you get the right answer?After how many tries?


Sounds familar? Fermat's principle states that:
    The path of a ray of light between two points is the path that minimizes the travel time.
    We can derives Snell's law from the relation found above L1

    where index of refraction n1 = c / v1,
      c is the speed of light in vacuum, and v1 is the speed of light in the medium.

    This is also true for other waves (e.g. sound wave) propagation between two different medium.


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 TIME
There are 2 translations,
Higher number at the end means more translation been done.
or
Logged
kristianly
Newbie
*
Offline Offline

Posts: 2
2 L1/L2
« Reply #1 on: October 04, 2004, 09:16:52 PM »
Dear Sir, what do you mean by L1/L2? I don't quite understand how the applet works. At a certain angle, the red path will take the least time (same as blue path). What does different is xx pt mean? The picture shows the source can be along the surface instead of the corner. Is it possible?

Thanks,
Christian Lee
NIE, Singapore
Logged
Fu-Kwun Hwang
Administrator
Hero Member
*****
Offline Offline

Posts: 1966


WWW
« Reply #2 on: March 04, 2007, 11:13:58 PM »
I am sorry. Our server was attacked by a hacker several months ago. Some of the files were deleted and I had to restored files from previous archive. And I restored an old version of this applet. There is no L1/L2 shown on the applet. Now, the latest and improved version is restored. Thank you!
Logged
Fu-Kwun Hwang
Administrator
Hero Member
*****
Offline Offline

Posts: 1966


WWW
« Reply #3 on: June 16, 2009, 10:16:41 AM » posted from:Taipei,T\'ai-pei,Taiwan
The following is a similar version created with EJS.
You can drag the star point (at the top) and end point(at the bottom) horizontally.
The velocity v change the moving speed.
Speed at upper half v1=v/n1, speed at lower half v2=v/n2.

This work is licensed under a Creative Commons Attribution 2.5 Taiwan License
  • Please feel free to post your ideas about how to use the simulation for better teaching and learning.
  • Post questions to be asked to help students to think, to explore.
  • Upload worksheets as attached files to share with more users.
Let's work together. We can help more users understand physics conceptually and enjoy the fun of learning physics!
Logged
Pages: [1]   Go Up
  Print  
"Make priority, take action and start now." ...Wisdom
« previous next »
 
Jump to:  


Related Topics
Subject Started by Replies Views Last post
I find this site is fantastic, especially billiards
Wave 		0 14966 Last post March 04, 2004, 12:20:42 AM
by
What will happened if part of the light path were blocked
Optics 		Fu-Kwun Hwang 2 15222 Last post January 01, 2010, 11:32:47 PM
by Fu-Kwun Hwang
how to find the sum of an array
Questions related to EJS 		lookang 5 2698 Last post December 19, 2008, 07:51:37 AM
by lookang
how to move particles along a path
Questions related to EJS 		Fred Chuit 1 1848 Last post December 30, 2008, 04:20:02 PM
by Fu-Kwun Hwang
Find out the time both particles have the same speed?
Physics Questions 		Fu-Kwun Hwang 0 478 Last post October 02, 2009, 10:40:00 PM
by Fu-Kwun Hwang
Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!
Page created in 10.401 seconds with 23 queries.