Laser Jell-O

When light interacts with another substance, it does one of three things: reflects, absorbs, or transmits. This experiment will help you understand transmission and absorption.

Materials

  • 2 Petri Dishes
  • Red Jell-O
  • Red and green laser pointer (CAUTION: never point lasers at anyone, they can blind instantly)

Directions

  1. Prepare Jell-O according to instructions
  2. Pour about half an inch of the red Jell-O into one petri dish and half an inch of the blue Jell-O in the other.
  3. Hold the red laser flat against the table and shine it into the Jell-O. Does the light pass through it or not?
  4. Do the same thing but with the green laser. Again, does it shine right through or not?

Explanation

When light interacts with another substance, it does one of three things: reflects, absorbs, or transmits. In this case the laser is either being transmitted or absorbed. The red dye in the gelatin doesn’t absorb red light, so it can clearly be seen passing through the Petri dish. However, it does absorb the green light. This can be attributed to the fact that gelatin is colloidal and scatters enough of the laser beam to make it visible.