A laser beam can be made visible by passing it through a glass tank of water into which has been added a little milk. Chalk dust from beating two erasers together will also make a laser beam visible. In contrast to white light, it can be seen that a laser beam doesn't diverge with distance. When the beam hits the surface of the water, it can be seen to be bent away from its otherwise straight path.
|erasers with chalk dust||017-21E|
|glass tank||021-21D or 021-21E|