6A44.20: Critical Angle
Description: With a small tank of water, you can use a laser beam to show the critical angle.
- Large glass container
- High intensity Laser
- Portable stand
- S clamp
- Milk powder
- Fill the tank up with water.
- Add a little bit of powdered milk. Mix it in.
- Mount the laser on the stand. The high intensity laser must be used for this to be most effective.
- Aim the laser into the tank so that total internal reflection occurs. Plug in the laser.
- Turn on the laser.
- Turn off the lights.
- Note that the laser beam experiences total internal reflection, and travels down the container walls.
- When finished, turn off the laser.
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.