6A02.35-Laser and Chalk Dust

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Description: This demo shows the linear nature of a laser beam by releasing chalk dust or fog in the lasers path.


  • laser on stand
  • black board eraser (with chalk dust) or aerosol fog

Demonstration Procedure:

  1. Turn on the laser.
  2. Turn off the lights.
  3. Clap the eraser or spray the fog in the path of the laser
  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.