By using lenses and mirrors, you can bounce, shift, reflect, shatter, and split a laser beam. Since the laser beam is so narrow and focused, you’ll be able to see several reflections before it fades away from scatter. Make sure you complete the Laser Basics experiment first before working with this experiment.
You’ll need to make your beam visible for this experiment to really work. There are several different ways you can do this:
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1. Take your laser with you into a steamy bathroom (which has mirrors!) after a hot shower. The tiny droplets of water in the steam will illuminate your beam. (Psst! Don’t get the laser wet!)
2. If you have carpet, shine your laser under the bed while stomping the floor with your hand. The small particles (dust bunnies?) float up so you can see the beam. Some parents aren’t going to like this idea, sooo….
3. Drop a chunk of dry ice (use gloves!) into a bowl of water and use the fog to illuminate the beam. The drawback to this is that you need to keep adding more dry ice as it sublimates (goes from solid to gas) and replacing the water (when it gets too cold to produce fog).
Materials:
- large paper clips
- brass fastener
- index card
- small mirrors (mosaic-type work well)
Download Student Worksheet & Exercises
Here’s what you do: Open up each paper clip into the “L” shape. Insert a brass fastener into one U-shape leg and punch it through the card. Hot glue (or tape) one square mirror to the other end of the L-bracket. Your mirror should be upright and able to rotate. Do this with each mirror. (You can alternatively mount each mirror to a one-inch wooden cube as shown in the video.)
Turn on the laser adjust the mirrors to aim the beam onto the next mirror, and the next! Turn down the lights first and use any one of the methods mentioned above to make your laser beam visible.
What’s happening? The mirrors are bouncing the laser beam to each other, and the effect shows up when you dim the lights and add fog or dust particles to help illuminate the beam. A laser beam is a highly focused beam of light, and you can direct that light and bounce it off mirrors!
Why can’t I see the beam normally? The reason you can’t see the laser beam without the help of a steamy room, dirty carpet, or fog machine is that your eyes are tuned for green light, not red (which is why you can see the beam from a green laser at night).
Exercises
- The word LASER is actually an acronym. What does it stand for?
- What type of laser did we use in our experiment?
- Why can’t we see the laser beams without the help of steam, dirty carpet, etc.?
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