Wave Phenomena Interactive Lesson

Part One:  Observe phenomena!

1. Use an equilateral prism – observe light entering and exiting parallel to one side and observe light entering and exiting along lines at angles less than 45° relative to the surfaces of two sides.

2. Use a tone generator – listen to the sound of a single speaker, then listen to the sound of two speakers connected with the same polarity and then with opposite polarity.

3. Use a mechanical wave generator – observe the resulting pattern when a wave is reflected back upon itself.

4. Use a diffraction grating – observe the resulting patterns when lasers of different colors pass through.

Part Two:  Definitions – fill in the blank! 
Use the words:  absorption, diffraction, dispersion, interference, opacity, reflection, refraction, transparency.

1. _____________________ occurs when a wave “bounces off” a surface or boundary between two different materials or media – the direction of the wave is changed but it remains in the same material or medium.

2. _____________________ is when a wave bends due to a transition into a different material or medium – the direction of the wave is changed along with the medium through which it travels.

3. _____________________ is a slight difference in the amount of refraction caused by difference in the wavelength and frequency of the wave.

4. _____________________ occurs when the energy of the wave is absorbed or transferred into a material.  The wave ceases to exist.  The extent to which this occurs determines the degree of _____________________ or _____________________. 
(transparent = wave passes through,  opaque = wave cannot pass through)

5. _____________________ occurs when two or more waves meet in the same medium.

If the combined effect results in greater amplitude it is called constructive.

If the combined effect results in lesser amplitude it is called destructive.

6. _____________________ is the bending of a wave around the edge of an obstacle.

Part Three:  Use simulations!
Model the above phenomena and explain the phenomena from Part One in terms the definitions.

Using the PhET simulation Waves on a String set up the following:

This shows two different wave pulses moving in the same medium – send a second one after the first one is reflected by the loose end.  Then observe the behavior for a while.

· Do the pulses pass through one another or bounce off one another?  How can you tell?

· Under what circumstances does constructive interference occur?  destructive interference?  How can you tell?

· Which wave phenomena observed in Part One of this activity is/are related to this simulation? 

Using the PhET simulation Wave Interference set up the following:

Place the pressure detectors as shown – one in a blurry gray region and the other in a region with alternating bright and dark.  Without moving the detectors try turning one speaker off and observe for a while.  Then turn it back on and watch what happens.

· Under what circumstances does constructive interference occur?  destructive interference?  How can you tell?

· Which wave phenomena observed in Part One of this activity is/are related to this simulation? 

Using the same PhET app Wave Interference shown above experiment with the tabs at the bottom of the window that are labeled Slits and Diffraction. 

· Which wave phenomena observed in Part One of this activity is/are related to these simulations? 

Using the PhET simulation Bending Light set up the following:

Now experiment with the position and orientation of the prism and laser and try to determine how the light was passing through the prism when you did the experiment.

· Try arranging as shown above and switch to the color laser – without changing position or orientation of the laser or prism adjust the color of light and observe what happens.  Why does this happen?

· How can a prism like this cause an object to look upside down?

· Try checking on the Reflections box and observe the effect – with this option it is more realistic how light would behave.