Science Buddies: "Ask an Expert"

Hi,

My son is wanting to do this experiment with a laser for his 7th grade science fair experiment. Can you let me know what you think and what challenges he may have.... Suggestions welcome!

The test is will changing the atmospheric conditions affect the accuracy of a laser pointer. The experiment will have a laser fixed a one set hight and then setting up a bull's eye type of target at a fixed distance away from the laser. He would point to laser and mark that it is center on the target. Then he would change the atmosphere by introducing fog conditions from a fog machine... note where the laser points to on the bull's eye and what is the distance (if any) away from the center of the target.

He is uncertain at this point the exact types of atmospheric conditions to introduce so suggestions are welcome!

He wants to perhaps use smog conditions by using the exhause of an old truck. As long as the laser is set at a set distance from the starting point to the target we could move to the back end of a truck to point the laser through the exhaust. This may be challenging if we cannot collect enough exhaust.

The other though is to set the experiment up with rain condiions... by using the sprinklers.

We would love any ideas for this possible experiment!
Thanks all

Hi Turbo,

What a fascinating experiment! You are testing fog, smog and rain--the most common atmospheric effects. The only other one I can think of would be the shimmer effect caused by heat. You could set up a hot plate or electric heater one foot below the beam and turn it on. As the air heats, it rises causing the rippling you sometimes see above a hot asphalt road. That might alter the laser beam.

If you can't get enough car exhaust, you could build a smoky fire in a barbecue grill under the beam to test the effects of smog. There's a bad fire raging in California right now and I bet there's a lot of smoke in the air. When that volcano in Iceland erupted a couple years ago, the smoke was so bad it interrupted airline flights.

How long is the distance from the laser to the bulls-eye and the distance from where you introduce the atmospheric change to the bulls-eye? These distances may affect the degree of shift of the beam spot. You should test this first, I think. Also. Can you activate the laser without moving it? That would be critical, especially if the distance from the laser to the target is long. Just a tiny movement of the pointer could translate into a large shift in the position of the beam spot.

I hope I have given you some more things to think about in your project. I like your creative approaches and hope you continue to post your questions and progress to this forum.

Best wishes,

Sybee