Experiments To Show Children

I have no intentions of using high power to demonstrate burning and all the "fun" stuff, but can anyone come up with some edumicational demonstrations to safely show children?? If need be I can use a <1mw red <5mw Green and <20mw green, but the higher powered experiments will be shown using video rather than direct exposure. This is for my friends children and thought it might be fun for them, along with some explanations as to the results.

I did see a great demo on Youtube that shone the beam through a sheet of glass edgeways, am assuming the wave pattern is due to light slowing down and we can actually see it's wave pattern. I have now lost the link and would appreciate it if anyone has this and any ideas to keep the little blighters interested for more than 30 seconds!! Please bare in mind that I last did Physics at school nearly 30 years ago and am more than a little rusty on the subject

Thanks in advance

Maybe you could get a diffraction grating or two, and if you have a low-powered blu-ray you could always show them some fluorescence and supercharge some GITD stuff.

Popping a black balloon inside a clear balloon would be plenty educational IMO.

13oots2 said:

...shone the beam through a sheet of glass edgeways, am assuming the wave pattern is due to light slowing down and we can actually see it's wave pattern.

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That's much less likely than you think... Slowing light is serious business which you'll not likely accomplish with a pane of glass. I'm thinking what you were seeing is the internal reflection of the beam, bouncing back and forth between the two surfaces of the glass. It's the same principle that fiber optics use. http://en.wikipedia.org/wiki/Total_internal_reflection

[highlight]Slowing light is serious business which you'll not likely accomplish with a pane of glass.[/highlight]

Almost any transparent medium will refract (slow) light to some degree, glass, and water are just a couple of examples. Soon as I get 10 posts under my belt I will do a serious search for the link and post it here. It might well not be what I think it is, but it sure looks good ;D

LRMNmeyer said:

Popping a black balloon inside a clear balloon would be plenty educational IMO.

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While educational, its not very spectacular to do - i've tried and all that happens is puncturing the black balloon wihout any pop, it just empties slowly. This is good to teach about relative pressures.

Total internal reflection whould be nice to demonstrate in water, like an aquarium - you could even add a bit of milk or something to make it visible with safely low power levels.

Excellent subject ! While this MAY not be what you are looking for - I have several children in my neighborhood that are very interested in lasers, and have held, "Workshops" with them, and their parents showing off some lasers, and even building some lasers, 5mw mostly, but some of higher powers for the older teens, and/or their parents - I provided safety goggles for each of them to wear while showing them off - and had a great time doing it ! You can purchase some very low powered red modules from sure electronics, and go about creating some low powered lasers if you want - some electronics knowledge will ACCIDENTALLY rub off on those that attend, which was a very desirable side effect Depending on the age group(s) involved - you can have a blast teaching them the safety rules, of both working with electronics, and with the safe and responsible operation of lasers ! I know I did - and now I have a herd of geeklings that pop over once in a while, asking for help with their shiny new hobby - and something to discuss with their parents, over coffee, tea, etc - it's been a lot of fun for me, personally, and I know the kids have enjoyed all of it as well ! not to mention the fact that by doing this, I have encouraged kids to learn the safe way, how to be responsible, and how to have fun whilst doing it - and made some interesting friends out my neighbors as well !!

Wow - sorry for being so long winded, and most likely not answering your question - but a few neat things (yeah - I'm an old fart...I say, "swell" too ! Okay...not really swell...but you get the idea) to do would be to create a time tunnel device, a spirograph, you can setup a maze with mirrors, and show off some cool things that way as well - basically - show them how fun YOU think they are, and they will catch the fever as well

Benm said:

[quote author=LRMNmeyer link=1230363563/0#2 date=1230432506]
Total internal reflection whould be nice to demonstrate in water, like an aquarium - you could even add a bit of milk or something to make it visible with safely low power levels.

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If you are using a violet laser, you can "swish" the tip of a yellow highlighter around in the water first. The ink dissipates quickly and fluoresces in the water when the violet laser is shined into it. It is very impressive

Peace,
dave

Show internal reflections using a stream of water. The first time I ever experienced lasers was when my technology teacher in middle school showed me that.

Hello All,

I can think of a couple that haven't been mentioned:

1. Optical Trapping- This is one of the coolest things to do with a handheld burner. It works with every wavelength I've tried. One basically focuses the laser very close-in (FP in inch or two from the lens) burn something and slowly pull the focus of the beam out of the smoke. If you do it right you'll grab a few smoke particles at the focal point. It looks like a glowing dot. Very cool.

2.Power vs. Apparent Brightness(requires LPM)- Get a 125mW blu-ray, a 300mW red and a 50mW green(or some such mix of colors/powers). Have the kids rate the relative brightness of the beams after viewing them. (they'll invariably guess green is the strongest.) Then use the LPM to show them which is actually more powerful. Great basic experiment as it shows children the difference between observation and measurement.

cheers,
kernelpanic

This thread is great. Anything that gets kids excited about learning is really an increadable think.

I used to give presentations at schools (usually during the math and science festival) showing off my laser projector. Once all the kids were seated I killed the lights and ran a full color graphics show with the music cranked up. Then I would talk about who I was, what a laser is and the laser I used to do this, the electronics, laser safety and then take questions. I would close with another laser show. The whole thing lasted about an hour. I would do this all day as they rotated as many students they could fit in the auditorium.

I would explain how to make their own simple laser projector. Just get an old radio, a small mirror, and a pointer then glue the mirror to the speaker point the laser into the mirror and turn the music up.

Keep up the good work. It's worth it. I loved it.

Two words: Blu-Ray Laser.






Just show them fluorescence and phosphorescence, that's the coolest stuff