# How to make a capacitor

One can make a homemade capacitor using an aluminum foil and a plastic or a wooden stick (it's important that the stick is an insulator). Make a small ball out of the aluminum foil and wrap it around the stick. Then make a wider foil sphere around the ball so that they don't touch, and your capacitor is ready!

If the radius of the smaller ball is $$5~\mbox{cm}$$ and of the bigger sphere $$15~\mbox{cm}$$, which capacitance in pF do you expect to obtain?

Details and assumptions

• The ball and the sphere are centered around the same point
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