NTNUJAVA Virtual Physics Laboratory
Enjoy the fun of physics with simulations!
Backup site http://enjoy.phy.ntnu.edu.tw/ntnujava/
August 22, 2017, 10:30:44 am *
Welcome, Guest. Please login or register.
Did you miss your activation email?

Login with username, password and session length
   Home   Help Search Login Register  
Ask questions. Follow-up questions. ...Wisdom
Google Bookmarks Yahoo My Web MSN Live Netscape Del.icio.us FURL Stumble Upon Delirious Ask FaceBook

Pages: [1]   Go Down
Author Topic: Physics of rainbow (EJS version)  (Read 9598 times)
0 Members and 1 Guest are viewing this topic. Click to toggle author information(expand message area).
Fu-Kwun Hwang
Hero Member
Offline Offline

Posts: 3080

Embed this message
on: February 12, 2010, 06:23:04 pm » posted from:Taipei,T\'ai-pei,Taiwan

When white sunlight is intercepted by a drop of water in the atmosphere, some of the light refracts into the drop, reflects from the drop's inner surface, and then refracts out of the drop.
As with the prism, the first refraction separates the sunlight into its component colors, and the second refraction increases the separation. The result is the rainbow.

The following applet shows many light rays heading for the water drop (white circle).
Because the incident angle are not the same for different incoming ray, the second refraction ray coming out at different angle.
The question is why we always saw the rainbow at a fix angle relative to the sun ray?

Embed a running copy of this simulation

Embed a running copy link(show simulation in a popuped window)
Full screen applet or Problem viewing java?Add http://www.phy.ntnu.edu.tw/ to exception site list
Press the Alt key and the left mouse button to drag the applet off the browser and onto the desktop. 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!

You can click the "real intensity" checkbox to find out the relative intensity for different paths.
You can drag the black square near the left side of the simulation to drag those rays up and down.

You might notice that intensity for incoming rays are not the same. It is indicated that the cross section are not the same for different ray.
If the ray is off by the center of the water drop by distance b, and the rasius of the circle is R.
The incident angle \theta, where \sin\theta=b/R, the effective cross section is proportional to \cos\theta

If the index of refraction is n, the refracted angle \phi, where \sin\phi=b/R/n ( i.e. sin\theta= n \sin\phi).

If the intensity of incoming ray is I, then the intensity for the reflected ray(s wave) is I_r=\frac{\sin^2(\theta-\phi)}{\sin^2(\theta+\phi)} I and the intensity for refracted light is I'= I-I_r

The above formulas are used to calculate the intensity for different ray.
I hope the above simulation can help you understand more about the physics of rainbow.

You are welcomed to check out physics of Rainbow for more in depth discussion about rainbow.

You can find more information about rainbow from http://www.atoptics.co.uk/bows.htm

* rainbow.gif (13.98 KB, 721x390 - viewed 486 times.)
Pages: [1]   Go Up
Ask questions. Follow-up questions. ...Wisdom
Jump to:  

Related Topics
Subject Started by Replies Views Last post
physics of Rainbow « 1 2 »
Fu-Kwun Hwang 39 541018 Last post June 02, 2015, 02:06:40 pm
by michael00
Diffeerent Languange version
Mirror sites and different language versions
Fu-Kwun Hwang 5 21709 Last post January 09, 2017, 12:25:33 pm
by smily
Manufactured Rainbow
Harbinger 1 16420 Last post February 20, 2006, 10:52:58 am
by Fu-Kwun Hwang
Physics of rainbow (EJS version)
ahmedelshfie 4 9379 Last post October 01, 2010, 12:13:12 am
by ahmedelshfie
Physics of rainbow (EJS version)
Questions related to EJS
ahmedelshfie 4 7160 Last post May 12, 2010, 11:30:28 pm
by ahmedelshfie
Powered by MySQL Powered by PHP Powered by SMF 1.1.13 | SMF © 2006-2011, Simple Machines LLC Valid XHTML 1.0! Valid CSS!
Page created in 0.716 seconds with 22 queries.since 2011/06/15