SAFE STATIC ELECTRICITY
LINK TO SAFE STATIC ELECTRICITY
You'll learn more physics from this one than you know what to do with
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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
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
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
Although quite difficult to make, a wimshurst machine is more reliable than a VDG; this is one I made from two CDs
The brushes are made from a thin brass wire wrapped round a thicker copper wire. The copper wire can be bent so that the brush is close to the disc
CDs will shatter if spun too fast,especially if weakened by sanding and electric sparks. This arrangement can only spin them at about 3000 rpm.
Mythbusters shattering CDs at 25,000 rpm
There is a much greater danger of the foil segments coming off if inadequately glued
The machine can be used without further elaboration; it will show areas of corona if viewed in the dark, or it will work an electroscope or give you minor electric shocks. However a charge collector can be made from a sheet of plastic laminated with cooking foil. This one has also been re-inforced with some cardboard. It's held with the jaws of the collector over each side of the wheel. This can accumulate a dangerous charge, all the more dangerous for looking so innocuous
It can be used to demonstrate electrostatic paper adhesion, and can hold down a tissue-paper stencil for printing with an airbrush or paint spray
This is a leyden jar, two of them connected by a wire can be used to collect charge from opposite sides of the wheel. The 'C' made from brass wire is held over the periphary. They shouldn't be held without careful insulation. Although the machine is small it can give quite powerful electric shocks
This one is worked with thumb & forefinger of both hands, it generates a spark about 4mm long (10KV) and is fine for printing and demonstrating faraday's bells. Very cheap to make, the bearing is made from a bit of 3mm rod with some plastic sleeving and two cheap pulley wheels; two gearwheels to hold the axle in place. It's a bit awkward bending the wire neutralizing brush holder so that it avoids your hands when they are turning the wheels. The charge-collecting combs are just made from single bits of bent wire, it doesn't matter if they occasionally touch the discs although ideally they need to be as close as possible without touching. In this design the leyden jar has one bit of foil all the way round inside the bottle but two seperate bits on the outside, this creates two capacitors in series
flying bits of polythene using static electricity
fun fly stick
another DIY generator; I haven't tried it
another DIY generator
early radio detectors
how to make ball lightning
high voltage from a 9 volt battery
very simple high voltage transformer
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