static electricity
SAFE STATIC ELECTRICITY
LINK TO SAFE STATIC ELECTRICITY
You'll learn more physics from this one than you know what to do with
LINK TO EXCELLENT STATIC ELECTRICITY SITE
This is a picure of making a charge collector for a van der graaff generator.
This is a capacitor + spark gap + collector comb made from a plastic pudding bowl, some sellotape and a small amount of aluminium foil. It's charged by rubbing a length of pvc waste pipe with a paper towel and passing the pvc tube over the pickup comb.
This is the same thing from underneath. The conductor is held at the spark-gap end with a bit of blue tack so you can adjust it. I found I could make quarter-inch sparks.
make an electrophorus
This is a van de graaff generator which can be made without any special materials or skills.
It is made from six plastic bottles: two uprights and two rollers each of which is made from the ends of two plastic bottles. Bottles with bulges at the top are best for making the rollers. The bearings at top and bottom are made from bent wire, this allows adjustment of the rollers so that the belt stays on; the belt shouldn't go too fast or it vibrates. The brush at the top should just touch the belt. It is all stuck together with sellotape, in practice it's a good idea to hold the two bottles together with a cross-brace made from cardboard or styrofoam.
Your hand both holds the machine with a loop of wire and rubs the belt as it rotates, because your fingers are very sesitive they can sense the friction on the belt. Use your free hand to bring an empty beer tin near the charge collector to form a spark gap.
How it works
This only works intermittently so there is a lot of scope for improvement. When it does work I find experimenting compulsive, because it's made without any resources you aren't afraid of making radical changes.
ask mr science. About half-way down
kelvin's thunderstorm
This is a static generator that can be made from very simple materials, it is a thunderstorm in miniature. Water flows from a cup down two drinking straws; the third straw crossing the 'A' is just to support the wires & rings
the foil rings become charged and attract the water droplets, spreading them out
As electric charge accumulates on the plate the droplets are repelled & float around without landing. Some of them try to get across to the other plate. If you make a spark-gap between the two plates you can get sparks, but I thought the floating droplets in themselves were a sufficiently impressive phenomenon. You don't need the foil at the bottom of the plates, a thin puddle of water works just the same.
To make a fine stream of droplets I made jets out of bits of insulation
They are sealed into the bottoms of the straws with bluetack
This is a detail of one of the foil rings: each one is connected to the opposite plate by a length of wire. I think it might be worth experimenting with changing the proportions
The straws are sealed into the cup with bluetack. They are a good way of creating a lage head of pressure without needing to use much water however when you first fill the cup airlocks usually form in the straws. You can clear them by poking a bit of wire down the straw.
I think my success with this may have been due to exceptionally dry weather, I think the droplet formation may be especially dependent on humidity
youtube movie
I simplified this one to get my version
how to measure humidity
make a cloud in a bottle
another method for making a cloud in a bottle
another interesting condensation experiment
water bridge
collecting charge from a single drinking straw
Static can be induced by rubbing a drinking straw with a paper tissue, the electricity can then be collected
In this case it's being collected on a capacitor made of two circles of foil stuck on top & bottom of a circle of foam
the electricity is drawn from the straw onto the middle of the collector by a strip of foil which just touches the straw as it slides past. I have used a short bit of wider straw to make the slider; the folded tissue is stuck to the other end with some sellotape.
Although the results are not very impressive a prototype can be made and tested in a few minutes, so meaningful experiments can be done very quickly. This shows the top surface of the capacitor with a strip of polythene that acts as an electroscope
A better charge collector which produces audible sparks can be made like this
More attention needs to be paid to the design of the charge collecting comb, this is just four bits of foil radiating from the point where the straw slides back & forth. The paper baffle supports the foil ring and the four strips
This is the other side of the baffle showing the paper tissue rubbing on the straw
Once the design principals are understood it can be scaled up using a bit of waste pipe
youtube movie
wikipedia
flying bits of polythene using static electricity
fun fly stick
another DIY generator; I haven't tried it
another DIY generator
more ambitious
early radio detectors
interesting link
magnet lab
how to make ball lightning
tesla coil
high voltage from a 9 volt battery
very simple high voltage transformer
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My email davidvwilliamson@hotmail.com