6A02.35-Laser and Chalk Dust

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Description: This demo shows the linear nature of a laser beam by clapping a blackboard eraser near it.
This can also be done with a can of compressed air (fog in a can will work too).


  • Laser on stand
  • Compressed air or black board eraser

Demonstration Procedure:

  1. Turn on the laser.
  2. Turn of the lights.
  3. Spray some compressed air in front of the laser, or clap a black board eraser in front of it.
  4. Note that you can now see the laser beam because the laser light is scattered off the particles and enters your eyes.
  5. When finished, turn off the laser.

Laser Light Laser Light
Do not stare at the laser beam. Do not point the laser at students.

Note: This picture is time elapsed. In person, the beam will not be as bright.