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.
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.