Battery #1 Making your own battery

Here is how to make a mustard battery.

Materials:

brass washers *
zinc-plated steel washers *
a piece of aluminum foil (5 cm square) *
paper disks just wider than the washers *
small bottle of runny mustard * (prepared mustard diluted with a little vinegar)
pipette *
buzzer * It's useful to connect a black clip-end wire to the black wire from the buzzer, and a red clip-end wire to the red wire.
light-emitting diode*

Making a battery:

Load the tip of the pipette with some of the mustard mixture (it isn't necessary to fill the whole pipette).

Put 2 small drops of the mustard on the top of a zinc/steel washer.

Place a paper disk on the washer.

Put two or three more drops of the mustard on the paper, over the washer. We want to get the paper damp but not dripping.

Place a brass washer on the paper.

Push down on the washer.

If any mustard oozes out, wipe it off of top and bottom (and use less, next time). The brass top and the zinc bottom should not have any mustard on them.

This makes a 0.7 volt battery. The zinc bottom is the negative end and the brass top is the positive end.

Make three more of these brass/paper/zinc batteries.

A single battery of this kind is not strong enough to cause anything to happen with any of our electrical devices. However, we can make a stronger battery by putting them in series in a stack. (Put the stack on the piece of aluminum foil. This will give a convenient way to provide an electrical connection to the bottom of the stack, which is going to be rather wobbly.)

Build a tower of two of the batteries on the aluminum foil, as shown. Always place them so that the brass washer is on top.
The stack of two sandwiches is equivalent to stacking two batteries end-to-end. It produces 1.4 V between the aluminum foil and the top brass washer.
It probably also will not do anything, but you could try to run the buzzer with it by connecting the negative (black) wire to the aluminum foil, and touching the positive (red) wire to the top brass washer.
Continue to build the battery by adding another layer of zinc/moistened paper/brass. Check it with both the buzzer and the light emitting diode.
Then add the last layer, and check it again.

It is important that the bottom side of the zinc washers stay dry, that the paper is damp, and that everything is in the right order.

You will notice that the battery works better if you disconnect it and let it rest for a few seconds. It may also help to push straight down gently, to improve the contact between the washers.

If your battery does not work, the most likely cause is that you have gotten parts wet that were supposed to be dry, or put the stack together in the wrong order. Break it up into the four sandwiches; if you find that they are wet on the outside, wipe them off with a paper towel. Then build the tower again.

When you are through studying the battery, take it apart and wash and dry the washers. As you do so, notice that the paper has becom stained, the mustard has turned brown, and the brass washer discolored. These are evidence of the chemical reactions that released the energy that the battery was producing. If you run the battery long enough, you will remove the zinc coating from the washer altogether.

When you are through studying the battery, take it apart and wash and dry the washers.