Favorite home experiments

[OmegaLord]

Surface-to-Air Potato Missile.

Best. Thing. Ever. Made entirely of PVC pip (and potato), one just loads it in, shoots some StaticGard in the other end, replace other end (by screwing it back on) and put lighter in hole. Light.
Cover ears.
Observe potato going really fast. I will post a diagram if anyone can tell me they will measure the speed of it!

[thecommabandit]

Take a grape cut it down the middle leaving a little bit of skin connecting two halves put in a microwave watch the plasma arc coming off the microwave.

Fix'd. I have nothing else to contribute.

[sigsfried]

It is surley an arc of current passing through the plasma (that being what my plasma physics lecturer said it was) I am willing to believe he is wrong but am not totally convinced.

[Robin S]

Plasma always carries current. I'm not sure whether the current would be arcing between the two halves of the grape, however. Even if your plasma physics lecturer said it was, he may have been oversimplifying. If you get a couple of minutes to talk to him, you could ask him to give a more detailed explanation.

[oxoiron]

Although it is a good electrical conductor, plasma does not require current to exist. It is merely ionized gas, which can be formed by applying extreme pressure and temperature, neither of which cause charge flow.

[Robin S]

However, the presence of ions and free electrons does cause charge flow. Plasma physicists will know that large-scale current flow arises spontaneously in plasma (the phenomenon is known as filamentation, unless I am mistaken).

[oxoiron]

Unless there is a net movement of charge, I wouldn't call it current. Areas of positive and negative potential moving around inside a plasma "cloud" do not current make. Charge entering one end and exiting the other end is current, although I suppose you could argue broadly that charge moving aimlessly within the plasma is also current.

[sigsfried]

Also plasma is meant to be clear isn't it? http://www.bnes.com/ygn/events/reactor/ ... okamak.jpg

However this wasn't a formal lecture talk this was him chatting to me duringthe summer when I was doing a research project (in reflection of BECs from an attractive potential) so I might not have been paying proper attention.

[evilbeanfiend]

It [plasma] is merely ionized gas

it is not merely ionised gas, the electrons in it have to be less than the debye radius so that they exhibit collective behaviour i.e. not all ionised gases are plasmas.

Also plasma is meant to be clear isn't it?

no e.g. the sun

[jtniehof]

it is not merely ionised gas, the electrons in it have to be less than the debye radius so that they exhibit collective behaviour i.e. not all ionised gases are plasmas.

I think what you meant to say is "the number of electrons in a debye sphere has to be large enough to exhibit collective behaviour." I'm not sure how an electron can be less than a unit of distance....

(And no, plasmas do not automatically have a current, and I have no idea how filamentation would be connected to that notion...)

[whatswithhumans]

i enjoy using pre 1982 pennies and using them to copper plate random metal things...

pretty cool to to have a polished copper quarter

[zenten]

So does my "plasma ball" at home contain plasma in it? If so, it would kind of shoot the whole in the entire "plasma always has arks without any current" idea.

[youshouldneverthrowacat]

This is worth a go...

EXPERIENCE SNOW BLINDNESS

Get a pingpong ball, cut it in half

Lie on your back looking up at a diffused light source (halogen light tube or equivalent)

Place a half of the ball over each eye so that you just see a uniform white surface.

Lie still without moving your eyes and blinking as little as possible

Experience snow blindness

Interrupt the uniform light (wave your hand) and the effect ends

[Aluminus]

Youshouldneverthrowacat as well as you should post in the intro thread first.

Van der Graff generator + Flourescent light tube = light saber!
You don't even have to plug it in! You just wave it between the sparks that you create and it lights up.

[scowdich]

Flourescent light tube + Tesla coil = teh awesomzorz.

And some twitching.

[d33p]

My favourite "experiment" is usually performed in a pub, with betting involved. I'll generally bet some poor schmuck that I can make *this* shot of whiskey and *that* shot of water trade glasses without using a third glass, and without spilling any. Once they've agreed to pay for the shot if I pull it off...

1) Fill one rocks glass with whiskey, as close to the top as possible.
2) Fill second rocks glass with water, right to the lip.
3) Take one playing card, place tightly over top of water-filled glass.
4) Carefully flip water-filled glass and card together, placing precisely on top of whiskey glass.
5) Slide the card a millimeter or so, just enough to allow a miniscule opening between the glasses.

As the water's denser than the whiskey, they'll gradually switch glasses. Pretty magical stuff to see, and you end up with one glass of slightly whiskey-flavoured water, and one double shot.

[Gem]

You can make a battery out of a lemon.

1. Get a lemon.
2. Stick a piece of iron (nails are good) and a piece of copper in the lemon
3. Connect them to anything with the batteries removed.

We did this with a stopwatch at school. It ran pretty slowly, but it still ran. Once it starts getting really slow, move the nail and copper to fresh pieces of lemon. It works better the more lemons you connect up to each other.

[oxoiron]

You could do this using different kinds of metal (e.g. Zn, Cu, Fe, Al, etc.) and record the clock speeds for each setup. By comparing them, you could determine relative reduction potentials.

[Aluminus]

I think Zinc/Copper was the best combo if I recall my electron-affinity tables. (It's been a couple years)

[el sjaako]

. Actually, that reminds me of something I've wanted to try for a while: the idea is to blow dry air through a metal tube which is cooled with liquid nitrogen. I expect liquid oxygen to condense in the tube and drip out of the end. Sure it's inefficient, but that's not the point!

I do a go-to-high-school-and-show-off-science! thing at my university, and we do something like this at every show. We take a pyrex bottle, put the pottom in liquid N₂, and carefully hang a soda can with the top removed over it. We fill the soda can with liquid N₂.

This causes liquid air to drip of the outside of the soda can, and into the bottle. After a while we take the pyrex bottle out of the nitrogen, put some matches in it, and then start dropping lit matches in it. Usually the first few fail, but at a certain point you get a pretty impressive flame.

There have been bottles that broke because of the heat difference (over 1000 dergees C at the top, and -200 at the bottom, as there is still liquid there).

We also solidify the nitrogen by putting it in vacuum.

[oxoiron]

I inadvertently made solid argon by doing something similar. I was filling a chamber around a liquid nitrogen cooled cold-finger with argon gas. It started to condense and drip onto the bottom of container. When I pulled a vacuum, the argon started to boil, but in doing so it lowered it's temperature enough to freeze into light fluff, at which point the remainder sublimed.

[shaper]

I'm surprised nobody has mentioned the potassium nitrate/sugar smoke bomb.

1) Melt sugar and potassium nitrate together (3:1 ratio or 1:3, I don't remember which, but I suspect triple sugar). KEEP THE HEAT LOW!! It's probably not a bad idea to do this on a hotplate outdoors. Melt the material in an old food tin, since you will wreck whatever container you use.

2) Before the caramel cools, stick "strike on anything" matches into the material so the heads are just sticking out of the goo.

3) After it has solidified, light the matches and enjoy the smoke.

I did this several times in high school and ended my smoke bomb career by filling an entire coffee can with goo and lighting it at halftime at a football game using the steel wool/nine volt battery thing super glucose mentioned above (by packing the top of the can with steel wool and inserting wires, I was able to use the battery as an ignitor from about 20 meters away, so I was able to remain hidden in a brushy area). It made a big enough cloud that the band had to leave the field.

EDIT: I should point out that the steel wool ignites the match heads, not the bomb itself. So, if you plan on using a steel wool trigger, you still need to embed some matches.

Encouraged by the success of the first batch, I doubled the recipe in the second batch. It got a little too hot. Fortunately, I was compensated for the loss of my smoke bombs with a four foot column of flame. Unfortunately, it was indoors. The table surface was destroyed by burning, splattering debris and we had to close half the building till the smoke cleared.

Surface-to-Air Potato Missile.

Best. Thing. Ever. Made entirely of PVC pip (and potato), one just loads it in, shoots some StaticGard in the other end, replace other end (by screwing it back on) and put lighter in hole. Light.
Cover ears.
Observe potato going really fast. I will post a diagram if anyone can tell me they will measure the speed of it!

The last time I did this a helicopter passing overhead came back and begin to circle. Left pretty quickly after that.

[oxoiron]

KEEP THE HEAT LOW!! It's probably not a bad idea to do this on a hotplate outdoors. Melt the material in an old food tin, since you will wreck whatever container you use.

Encouraged by the success of the first batch, I doubled the recipe in the second batch. It got a little too hot. Fortunately, I was compensated for the loss of my smoke bombs with a four foot column of flame. Unfortunately, it was indoors. The table surface was destroyed by burning, splattering debris and we had to close half the building till the smoke cleared.

I try to give good safety advice...

[shaper]

KEEP THE HEAT LOW!! It's probably not a bad idea to do this on a hotplate outdoors. Melt the material in an old food tin, since you will wreck whatever container you use.

Encouraged by the success of the first batch, I doubled the recipe in the second batch. It got a little too hot. Fortunately, I was compensated for the loss of my smoke bombs with a four foot column of flame. Unfortunately, it was indoors. The table surface was destroyed by burning, splattering debris and we had to close half the building till the smoke cleared.

I try to give good safety advice...

No, this was years ago. Fortunately it was in high school, not my own ceiling I blackened. : )

[schrodingersduck]

This is a fun one to demonstrate kinetic theory/rates of reaction etc. Plus, it looks really cool!

Take one or more glowsticks (preferably the thin and bendy sort, so they can be flexed into a circle). Activate them and then put them in the freezer for 10-15 minutes. When you open the freezer again, they should appear dead. Transfer them to a bowl with a little warm water and then add hot water from the kettle. The glowsticks begin to brighten until they look almost as bright as a lightbulb! For effect, choose lots of green glowsticks and add green food colouring to the water. The spooky glow and steam make the bowl look like a bowl of magic potion!

[Rook]

Flourescent light tube + Tesla coil = teh awesomzorz.

And some twitching.

You don't need a tesla coil, or even any obvious 'active' source of potential difference.

Just take said fluorescent light tube underneath some overhead power cables (of the long distance, national grid, 5MV variety). Exactly the same effect, and easier to obtain. If you don't mind the buzzing (which always freaks me out). I recall a newspaper clipping in my college science department that had a picture showing some 200 of these lights planted vertically in a field under said power lines. Apparently just for art, but I still don't like what it says about how much energy is going to waste.


Also, what the heck is StaticGuard?

[Delbin]

Just take said fluorescent light tube underneath some overhead power cables (of the long distance, national grid, 5MV variety). Exactly the same effect, and easier to obtain. If you don't mind the buzzing (which always freaks me out). I recall a newspaper clipping in my college science department that had a picture showing some 200 of these lights planted vertically in a field under said power lines. Apparently just for art, but I still don't like what it says about how much energy is going to waste.

Also, what the heck is StaticGuard?

That must have looked so cool! Isn't the energy use relatively low with florescent lights? As in, roughly trivial compared to loss due to heat? I'd imagine so if they glow with ambient energy.

StaticGuard is something you spray on clothes to stop them from clinging to other clothes or themselves.

[Rook]

Found it:

That's not the best picture, but there's plenty of worse ones.

From reading the articles around these, the light level produced is quite low, and occasionally odd tubes will flicker out (apparently touching the bottom gets them lit again). As to energy lost, I think it's only lost once you put the lights there (now I think about it), since it's the difference in electrical potential that's lighting them, not an electrical current.

[Cramulh]

Take the cap of an empty aspirin tube. There should be powder or crystals inside, to protect the aspirin from moisture.

I don't know what it is, but I've always been amazed by how hydrotropic this compound is. You can pour huge amounts of water on it before it gets saturated.

[oxoiron]

I'm guessing you meant to say "hydrophilic" and you reminded of another fun demonstration:

1) Cut open a disposable diaper (unused is best ) and collect the powder inside of it.
2) Place the powder in a glass and slowly add water.

This should produce a thick gel that will stick in the glass when it is turned upside-down.

3) Add NaCl on top of the gel and mix it in with a spoon.

This alters the absorbent properties of the super-absorbent polymer/crystals and should release a lot of water and liquify the gel.

[wst]

Take the cap of an empty aspirin tube. There should be powder or crystals inside, to protect the aspirin from moisture.

I don't know what it is, but I've always been amazed by how hydrotropic this compound is. You can pour huge amounts of water on it before it gets saturated.

Silica gel?

[Cramulh]

More like smalls crystals. It could be anhydrous MgSO4 or Na2SO4.

[J Spade]

The paperclip top.
A good one for at school, as well, during that boring English lecture.

In action:

[thecommabandit]

Care to explain how it works? I've never seen that one before.

[hyperion]

Care to explain how it works? I've never seen that one before.

You can read about them here.

[J Spade]

My best explanation:

1) Unbend a paperclip. As best as possible, and use the ones that are about 4 cm long when folded.
2) About 1.5 cm from the end, make a sharp, 90º bend in the wire.
3) Another 1.5 cm down the wire, from the same end, make approximately an 80º angle in the axis perpendicular to the previous bend.
4) Now curl the wire around the center, keeping 1.5 cm away from it, until you have about 4 cm left. The circle needs not be perfect.
5) Make another 80º bend into the middle
6) With the remaining wire (about 2 cm) Form the other half of the rotational axis.
7) Adjust the axis until perfectly straight and perpendicular to the circle.
8) Now check to see that the axis is in the perfect center by placing it on your fingers and seeing if it tends to roll to one side.
9) Spin it.
10) Tweak it more.
11) Spin it again.
12) Repeat until you see no blurring in the axis while it spins. (My picture has a bad example of this.)

Also, a better picture of the finished project:

[jeryd_zeryth]

i didnt read all the posts but did anyone include the emp cannon? i pulled this one off in middle school(or elementary?...)by wrapping a crap-ton of copper wire around some pvc pipe and hooking that up to 10 lamp batteries with a toggle switch so it went from on to off to negative as the punch or drill bit went through the tube. same idea as rollercoasters; pull, switch to push halfway through.

or a simple stupid one way back in my day (mid '90's) was the three sheet of paper-airplane, went all the way down a school corridor with a light throw when others couldnt get one across the classroom.

[AbNo]

Found it:
http://img511.imageshack.us/img511/6410/fieldci0.jpg
That's not the best picture, but there's plenty of worse ones.

From reading the articles around these, the light level produced is quite low, and occasionally odd tubes will flicker out (apparently touching the bottom gets them lit again). As to energy lost, I think it's only lost once you put the lights there (now I think about it), since it's the difference in electrical potential that's lighting them, not an electrical current.

Alternatively, try blasting light tubes with a healthy dose of RF power, out of say, a TRC-170, or a USC-60.

It was really fun making all the lights in base housing come on.

Too bad I don't do that anymore.

[Jakell]

Supercooling water has always been a favorite of mine. And you do not have to use just water either! Soda, fruit juice, flavored exercise water; all you have to do is put them in your freezer, and have it set to a few degrees below zero (C). If the bottle cools slow enough, you can supercool the liquid, and turn it into varying amounts of ice by hitting it. If you cool it to about several degrees below zero, it turns to mostly slush, but if you only cool it one or two degrees, you can actually watch the small ice crystals form- it will snow in the bottle! Pouring out supercooled water into a bowl is a good demo, because the water will turn into a sluch when it hits the bowl!

Also, a friend recently showed me this video:
http://www.metacafe.com/watch/1004040/
I have not tried it yet, but I probably will in the near future!

[LoopQuantumGravity]

Supercooling water has always been a favorite of mine. And you do not have to use just water either! Soda, fruit juice, flavored exercise water; all you have to do is put them in your freezer, and have it set to a few degrees below zero (C). If the bottle cools slow enough, you can supercool the liquid, and turn it into varying amounts of ice by hitting it. If you cool it to about several degrees below zero, it turns to mostly slush, but if you only cool it one or two degrees, you can actually watch the small ice crystals form- it will snow in the bottle! Pouring out supercooled water into a bowl is a good demo, because the water will turn into a sluch when it hits the bowl!

Also, a friend recently showed me this video:
http://www.metacafe.com/watch/1004040/
I have not tried it yet, but I probably will in the near future!

I like these ones a lot:
Self pumped vacuum capacitor
http://www.youtube.com/watch?v=FqDI0lFz9Gc

and
Dangerous high speed mag-lev
http://www.youtube.com/watch?v=glCNP6qH_Dc

and
Bare handed bottle smash (shockwaves caused by cavitation. I saw an interesting lecture about cool impact physics and shockwaves a year or so ago... you can do lots of neat stuff like this.)
http://www.metacafe.com/watch/780996/

If I had equipment, I'd do all of these. But I don't even have glass bottles .

Stuff like this almost makes me wish I were an experimentalist.

edit:
On the same website, I found this:
Experiments with traffic!
http://www.amasci.com/amateur/traffic/traffic1.html
http://amasci.com/amateur/traffic/trafexp.html