Q&A for How to Make a Potato Clock

As long as the wires and nails are not touching each other and are made of the specified materials, then they do not have to be the same size.

How long a potato battery will last depends on a lot of things. First, it will only be "used up" if it's actually hooked up to a wire. If it's not hooked up to a wire, it will theoretically last until the potato goes bad. Also, it depends on how much zinc you have, because the zinc gets used up in the reaction that powers the battery. If you're using a piece of metal that only has a little bit of zinc on it, then it won't last very long at all. But if you use a big, solid piece of zinc, your battery could go for a really long time! It also depends on the potato - some work better than others. If you want to know exactly how long a specific potato will last, the only way to find out for sure.

A potato clock runs by converting chemical energy into electrical energy, which is then used to power the clock. The potato, in combination with the zinc and copper strips (which act as electrodes), acts as a battery.

Each potato assembly is a cell, producing a certain voltage. In order to have enough voltage to power the clock, you need two cells or potatoes in series.

I would recommend making a lemon clock.

The best potato to use in terms of more and longer power is the Jersey Royal Potato. The second best is the Red Potato. Boiling your potatoes also helps bring the power up for your clock.

Yes, but it would have to be a penny made before 1982; those made after are made of zinc with a thin copper coating.

You can, but the penny would have to be from before 1982 because ones after that date are made with zinc and only have a slight copper coating.

It could be but you need to ask what the judges are looking for by way of challenge and originality. Potato clocks are a nice project to do but they might not win the fair because they are a common choice and not particularly challenging.