diffraction experiments

[Pedsam2]

I was asked this question by a student and would like to give a knowledgeable response, how should I respond to the following question:

"I would like to experiment with blue, red, and green 5mw lasers pointer pens for my physics class to use in diffraction experiments. I want to use these with diffraction glasses rated at 500 lines. They will pass through a diffraction grating and shine them on the other side of the wall in the classroom to measure the distance between maxima.. I know that most of the red lasers that I own are less than 5mW. Are these too powerful for this type of experiment?"

 

[icecruncher]

Usually the center line will still be the most powerful going through the diffraction gratings

That being said the word "most" bothered me in the statement

 

[viperx1101]

Usually the center line will still be the most powerful going through the diffraction gratings

That being said the word "most" bothered me in the statement

Yeah, I had to re-read the OP and saw that as well. (the "most" part...)

For Pedsam2, it will definitaly not be too powerful. Using a 500 line diffraction grating with a 5 mW laser should be adequate for the experiment. You will probably see a few lines on either side of the main line, but that would be all.

 

[The Lightning Stalker]

Anything 5mW or less will be reasonably safe. If
they are Chinese laser pens, there is a chance
they could be overspec, though. In that case, it
would be best to go to Wal-Mart or your local gas
station and pick up a "cat toy" laser <1mW.

 

[BShanahan14rulz]

Even with low power lasers, this would be a good time to practice safe usage. Goggles, or at least, knowing to use goggles before activate laser. Stable, level mounts at waist level, never eye level. Be careful of shiny things like jewelry and watches, they could redirect an otherwise safe beam up into an eye. A lot of it is common sense, but practice turns common sense into habit.

Lots of cool things can be done in science labs, but must always be done with safety in mind.