Tips and Tricks for Electrostatic Experimenters
    Spheres- Spherical shapes are common to electrostatic devices for a couple of reasons. One is that the "rounder" a shape is, the less it will leak charge into the air or onto nearby objects. Another is that the larger the radius of a charged sphere, the longer the spark is that can be drawn from it. Some sources for conductive spheres: Plastic- Not all plastics are created equal. In your research you may see a table or list of materials and their "dielectric constant". The dielectric constant is a reference for how good an insulator something is. Different plastics have different dielectric constants. The other reference you may want to be aware of is "breakdown voltage". Breakdown voltage is the voltage required for electricity to puncture a given thickness of a given material. I recently made a Leyden jar out of a plastic soda bottle and was disappointed to find that its capacitance was much lower than expected. It would charge to a point, then partially discharge itself through the plastic (this is a different phenomenon than spark over, which is when a visible spark travels over the edge of a Leyden jar). When it comes to building up a charge on plastic, these two references help explain why things behave the way they do. Take a look at a variety of plastic containers and try to find the letters that identify what kind of plastic they are made from. You may see PTFE, PVC, HDPE, PP, PETE, or something else. These initials stand for the name of the plastic. So far I favor HDPE (stands for high density polyethylene) for making Leyden jars. PVC is great for charging by rubbing. 
    Glass- I personally don't use glass very often, because plastic is cheaper and doesn't break when you drop it. If you do use glass though, be aware that it can have different dielectric constants too. Pyrex glass is different than plate glass, which may be different than the jar your mayonnaise comes in.

    Wax- Occasionally I have seen references to waxing surfaces that are to be charged by rubbing. The idea is that you polish some car wax, or paste wax on PVC and it helps to make a stronger charge with less effort. My own experience has been annoyingly inconclusive. I put carnuba wax on a sheet of  acrylic and now I can't seem to put a charge on it at all. I have put car wax on PVC and had mixed results. In one case out of many, there was a noticeable improvement with respect to the effort it took to create a charge. If you want to try this, do tests before waxing your favorite piece of plastic. My best results have been with liquid car wax.  

    Other Stuff- You may look at things a little differently after you get into experimenting with electricity. A soda can suddenly becomes ripe with possibilities. One person uses them for the spheres on his Van De Graaf generators. A disposable aluminum pie plate and a foam plate can be fashioned into an electrophorus without much trouble. If you take this same idea and use a sheet of acrylic or PVC you can get even bigger sparks.

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