having fun with lasers by aurora lipper

Lasers remind us of Star Wars and parties. Lasers are associated with fun and although many other educational programs such as the Apologia science curriculum have touched the surface, I want to delve deep and enable kids to safely experience lasers and their diffraction.

L.A.S.E.R. stands for Light Amplification by Simulated Emission of Radiation. The light emitted by an incandescent bulb spreads in all directions, and therefore lights up the room, while the light coming from a laser is in the form of a thin beam made up of photons travelling in a straight line. Therefore a laser beam makes just a dot of light on your wall. I have gone through many homeschool curriculums such as the Apologia science curriculum, and I felt that I must take learning one step ahead by introducing some practical and fun ways of learning science.

How Lasers Work
When a light source throws light into the tube of your laser pointer, the particles of gas in the tube begin to vibrate harder (imagine your excited pet dog running all over your living room). When these excited particles relax (imagine your dog lying lazily on the couch), they release light energy in the form of photons. These released photons now collide with other gas particles in the tube and make them vibrate or relax. After some time many photons of light are released. They bounce off mirrors in the tube and are released through the opening of the tube (imagine a doggie door) in a controlled manner, forming a thin and straight beam.

Now let's do a couple of fun experiments. You can use a keychain laser or a simple red-laser pointing device for the same. Green lasers from astronomy stores are dangerous and should not be used. Remember to wear eye protection even if it feels weird to wear them in the dark.

Beam through Bottle Experiment: Fill a plastic soda bottle with water. Add a few pinches of cornstarch till the water turns slightly milky. Now switch off the lights and flash your laser pointing device through the bottle. What do you see? Do you see the original laser beam? Can you find the reflected and the pass-through beam?

Laser-Fog Machine Experiment: You can do a slight variation to the above experiment by using a fog machine instead of cornstarch water. Turn on the fog machine and flash a couple of laser pointing devices through the fog. Enjoy the spectacular laser show!

CD Laser Diffraction Experiment: Place an old scratched CD and a new smooth CD on a table. Turn on the fog machine around the CDs, and flash the laser pointer on both the CDs. What do you see? Which CD sends out more reflections, the scratched one of the smooth one? See to it that there is enough fog so that the laser beams are seen clearly. You can also place other shiny objects near the CDs and enjoy the laser patterns!