Quantum Physics Science Advanced Project

[The12thDoctor]

So, I love physics and math. I have my first Science fair coming up, and I've dreamed about this day since I was five. Putting my knowledge into work that my peers can judge, and maybe spark interest in Physics for someone else. What project could I do that is Quantum Physics or really any non-elementary field of physics. Please keep in mind, I'm only 14 and this is AP. Am I aiming to high. I thought of the Double Split but something a crowd could learn from. ThanksSent from my iPhone using Physics Forums

 

[Simon Bridge]

Welcome to PF;
The classic quantum experiment is 2-slit interference - but that also works by wave-optics.
If you can get hold of florescent light bulbs, you can use interference to show discrete spectra.
The main restriction is what sort of resources you have - quantum experiments can get expensive very fast.
Maybe have a look at: http://www.diyphysics.com/

 

[Khashishi]

You can do double-slit with water, if you prefer. Then you don't need to muck around with lasers.
Other ideas:
chaos pendulum
Heron's fountain
Cladni plate
bicycle wheel angular momentum thing
Brownian motion with a microscope
Non-Newtonian fluids
motors (homopolar, etc)
van de graff generator
railguns, coilguns
radioactivity and photographic film (do they let kids get their hands on these things nowadays?)

 

[TheDemx27]

radioactivity and photographic film (do they let kids get their hands on these things nowadays?)

A couple years ago in eighth grade my science project was 2 things: A iron and magnesium battery, the electrolyte being table salt suspended in water. The second thing I made was a cloud chamber.

(I got the materials for my birthday) I think it cost around $60 US. Of course, you will have to keep on buying dry ice but it is well worth it. I think that the cloud chamber just looks cooler.

 

[CWatters]

The double slit experiment will demo the wave like nature of light but it's not so obvious how to demo the particle like nature in a way the public will understand at a science fair. Cern suggests...

https://teachers.web.cern.ch/teachers/archiv/HST2002/smallexp/kjepso/particlenature.htm

 

[DrewD]

Photo electric effect can be demonstrated using cheap LEDs, a 6V battery, and a multimeter. I think it takes more understanding to properly explain, but if it is done right, it is pretty cool. I did it outside for some elementary school kids and half of them didn't care at all and the other half were blown away. It isn't as flashy as the double slit or or a chaotic pendulum.

 

[Simon Bridge]

None of the ideas in post #6 involve quantum physics much at all.

It is difficult to do an experiment, cheaply, that demonstrates, unambiguously, the main points of QM.

i.e. Youngs interference has a wave-model for it, the cern one is cool - but the light pulse was very short and sharp, so a wave could have delivered the energy to make the plate ring (the ring would probably be different - but how would you show that in the experiment?) OTOH: it should be impressive for people.

The photo-electric effect should be good if you can set it up.
Trying to get the same effect from a wave model is tricky.

You can just charge an electrometer and discharge it by shining light on it - but that's not the quantum part.
You need to be able to show that "light delivers energy in lumps" is the easy way to model this.
But you never know - maybe your school has the equipment?
Maybe you have the money to buy the equipment?

If resources are good, then, there is always setting up an oven and spectrometer for blackbody radiation, Millikan's experiment, and a host of others.

Then again - at your level - maybe just showing the phenomenon and asserting the quantum description will be good enough for the science fair judges?

 

[DrewD]

The photo-electric effect should be good if you can set it up.
Trying to get the same effect from a wave model is tricky.

You can just charge an electrometer and discharge it by shining light on it - but that's not the quantum part.
You need to be able to show that "light delivers energy in lumps" is the easy way to model this.
But you never know - maybe your school has the equipment?
Maybe you have the money to buy the equipment?

If you use LEDs they can be used to absorb light. A blue LED needs a higher energy photon to create a current than a red LED. When you shine a blue LED on a red LED you get a current, but not the other way around. Including multimeter, the set up costs about $20-$40. The downside is that and LED is sort of a "magic box" that might not convince some people.

 

[Simon Bridge]

If you use LEDs they can be used to absorb light. A blue LED needs a higher energy photon to create a current than a red LED. When you shine a blue LED on a red LED you get a current, but not the other way around. Including multimeter, the set up costs about $20-$40. The downside is that and LED is sort of a "magic box" that might not convince some people.

In a wave delivery - the red light should eventually produce a current - when it has delivered enough energy.

The slam-dunk would be to show the absorption spectrum for the LED... requires a tuneable light-source.

The trick is to set up the wave theory predictions to disprove.
The black box effect can be mitigated by also showing the discharging electroscope.
Should be good enough for a science fair. Good call.

Perhaps: show heating metal by electricity to get light (light bulb) point out reverse is possible: discharge electroscope. Explain wave picture predictions. Repeat experiment with LEDs to contradict wave picture predictions. (current in = particular light out)?

I don't see any way to avoid some bold assertions.
But it should be fun.