Exploration 37.1: Varying Numbers and Orientations of Sources

Please wait for the animation to completely load.

This applet calculates seven frames and then runs continuously.  For a large number of sources, or for very small wavelengths, this calculation can take some time, so let the applet finish calculating all seven frames.

Two sources of light waves of equal frequency and amplitude are shown.  In the amplitude view the greatest amplitude is represented by white, negative amplitudes are represented by black, and areas with zero amplitude are represented by gray.  In the intensity view the greatest magnitude of the amplitude (positive or negative) is represented by white, while black shows regions of zero amplitude (position is given in nanometers).  Restart. 

  1. What would the pattern look like (in both the amplitude and intensity views) if one source were removed? Answer:   view with one source.           
  2. What is the wavelength?  (Check both the amplitude and intensity views.) 
  3. In which view do you measure the wavelength by measuring the distance from the middle of the white band to the middle of the adjacent white band, and in which view do you have to measure the distance across two white bands (or black bands)?  Why?
  4. What would the pattern look like if the two sources were in phase with each other but rotated 90o to lie on the x axis?  Answer:  rotate sources.    
  5. Explain why the pattern looks the way it does.    

 

 

Exploration authored by Melissa Dancy and Anne J. Cox.
Instructor's Resource CD Edition: Do not post or distribute.
The complete version of Physlet Physics is available as a text with CD; Physlet Physics can be bundled with this Prentice Hall textbook.
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