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24.8 Dispersion

Rainbow
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Instructions:
Click on the "Start Simulation" button to open the applet window. This applet runs automatically.  The circle represents a rain drop. You can change the color of the incoming light by pressing on the corresponding color square on the upper left of the applet. Right at the level of the center of the droplet, the radius of the drop (R) and the vertical position (b) of the incoming light ray relative to the center of the drop are provided. You can change b by clicking on the light ray with the left mouse button and dragging up or down. When using one of the basic colors, clicking on the light ray with the right mouse button and dragging changes the direction of the incoming light beam. The index of refraction of water for each of the basic colors is provided next to the color box. The incidence (i) and refraction (r) angles of the incoming beam are given at the bottom left of the applet. The numbers provided next to all beams refer to the polarization of the beam. '|' is used to refer to polarization in the vertical direction parallel to the screen and '+' is used to refer to polarization perpendicular to the screen. The graph shows the the electric field magnitude along both polarization directions, yellow for '+' and a basic color for '|.'
When in rainbow mode (white light, with small drops) you can drag one of the drops around.

Navigation: You can come back to this window by pressing the "Close Simulation" button on the bottom frame of the utility.  

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Explanation:
This applet demonstrates the dispersion of light by water drops and the formation of rainbows. The concepts involved are discussed in section 24.8 and 24.10.  
 
Source:
Fu-Kwun Hwang

Link to the following WebPage to get more information about the author.