Introduction to the Wave Program

 
(To be used with the Specs wave program)
 Purpose

The purpose of this activity is to give you the chance to "see" and explore the interaction of waves. In your everyday life you have probably experienced this type of interaction many times. This activity will allow you to control the interaction and help you to visualize what happens. How does the interaction affect the way you view your surroundings?

 

Words you should know

amplitude, constructive interference, destructive interference, diffraction, frequency, fundamental frequency, index of refraction, phase angle, and superposition.

glossary of terms
 Some background information
Wave applications to everyday life.
 
 

How to use the wave program

The vkwindow has six buttons: Start, Stop, Clear, Object, Delete, and Snapshot.

  • Start
    This is the top icon, in the vkwindow, it is the run button.

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  • Stop
    The "stop sign" stops the wave. This does not clear the display. If you click run again the wave will continue where it left off.

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  • Clear
    This will clear the display of the waves. It does not clear the objects that you have placed on the screen. To clear those you need to select each and press backspace/delete.

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  • Object
    The forth icon is the object tool. When you click on this icon you create an object with the characteristics you have selected in the simple Window. You can change these characteristics using the boxes provided. Note the object you are changing must be selected. You will know which object is selected by the white dot in the center of the object, or if the object has been rotated it will be in the top left corner of of the object. Note only the walls can be rotated.

     

  • Object placement in the vkwindow can be controlled by the location in the simple Window or by clicking and dragging the object to its new location. You can also use the arrow keys to move the object. If you hold down the shift key and use the arrows the object moves much faster.

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  • Delete
    If you wish to delete the object, select the object and then press the delete button.

     

  • Snapshot
    This button will allow you to take a picture of the vkwindow window. A dialog box will appear which allows you to save the image in a convenient location. The images may be viewed using Ipaste or other viewing software.


  • The dotted line with the yellow triangle, called the probe, sets the location where the wave will be graphed. This can be moved during a run. The counter at the bottom of the window tells you the location of the probe line. This will be useful in finding the separation distance between different in objects.
  • The simple Window is where you can change the size, shape, and color of the object. The rotation angle moves the object clockwise from the bottom. If you wish to rotate counterclockwise use negative numbers. The angle left and angle right have no effect on the wall or the oval. They only work on lens. You can change the frequency of the wave at anytime.

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  • The light bans are the crest of the wave, and the dark bans are the troughs.

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  • Note: If you place and object off the screen you can not get it back. Example, if you rotate an object and the top corner is no longer in the window you can not select it to move it to a new location, using the cursor. If you have not clicked on anything else you may be able to use the arrow keys to bring it back. Be Careful!

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  • On the graphWindow the copy button will make a copy of the current graph and change the color of the next graph. You may make multiple copies at one time, each one will be a different color. The clear button will clear all copies of graphs stored when you make the next run.

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  • The pink dot on the graph line represents the location of the cursor. At any time you can press the "D" key on the keyboard and freeze its movement in the "x" direction. It will still float on the wave in the "y" direction. Press the "D" key again to unfreeze the dot.

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    Wave Propagation Lab

    Step 1: Set the frequency to 40. Run the program.

     Step 2: Place the cursor in the vkwindow. Note the movement of the pink dot in the graphWindow. As the wave passes by the pink dot "floats" up and down but does not travel with the wave.

     Does this mean that the wave is transmitting energy, matter, or both?

     Step 3: You can see the crest and troughs of the wave front moving from left to right across the vkwindow.

    How does this relate to the image in the graphWindow?

    Can you see that the waves move in a direction that is perpendicular to the wave fronts. This is called rectilinear propagation or straight-line motion.

    Step 4: Make a copy of the graph by pressing the copy button in the graphWindow.

     Step 5: Now change the frequency to 20. Continue running the program and note the change in the wavelength.

    How did the wavelength change in relation to the frequency?

    Step 6: Try to change the frequency so that the wavelength is three times as great as it was with a frequency of 40.

    What was the frequency? How did you figure it out?

     

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