Wave Machine

Light is very strange in that it travels as both a wave and a particle. This activity will simplify this concept by building a wave machine to show how light moves as a wave.

Materials

  • Scotch tape
  • toothpicks
  • mini marshmallows
  • two cups

Directions

  1. Place the two cups about 14 inches apart
  2. Take your toothpicks and attach a mini marshmallow on both ends
  3. Roll out a little more than 14 inches of scotch tape and evenly space out the toothpicks onto it.
  4. Connect the cups with the tape. The sticky side should be facing up and both ends should be attached to a cup. If the tape doesn’t feel strong enough to hold up the toothpicks, put another strip of tape over the top of the toothpicks.
  5. Tip the toothpick on one end of the tape over and watch the movement of your wave machine.
  6. Now take the marshmallows off the ends of a little more than half of the toothpicks.
  7. Repeat step 5
  8. Observe the difference in speed between the half with marshmallows and the half without. 

Explanation

Light is very strange in that it travels as both a wave and a particle. However, in this experiment, we only look at light’s wave-like properties. Notice how when you tip one side of a toothpick up, the rest of the toothpicks follow in a motion that is similar to a sine function. This mirrors how a disturbance in light will carry throughout the wave and give off a specific frequency. When we take off half of the marshmallows, we see part of the wave machine moving in a faster motion. This demonstrates how a wave looks at a different frequency.