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An electric cell in your kitchen
Materials:
Binchotan (the resistance is about 10cm)
We can use activated carbon for deodorant instead of Binchotan.
Aluminium foil
leading cords
kitchen paper towel
salt

Binchotan is a kind of charcoal, activated carbon with low resistance.
This is made of oak with high temperature for about a month and then water is poured on it.

We can find these materials at any home utensils counter in a supermarket.
When we want to do any experiment, we can find suitable materials or utensils in these places easily. When we use materials or utensils not for common use. Natural laws exist in any place. We can do physics experiments with anything common.

Preparation:

1. You roll up a "Binchotan" with kitchen paper towel soaked with a solution of salt.
2. You roll it up with aluminium foil, and you will get the electric cell in your kitchen. N.B.: You never short between alminium foil and charcoal terminals.
3. You connect the electric cell with a motor for solar battery or a little one and switch on the circuit.

Reference: "Physics is exciting." edited by Yoji Takigawa in Japanese

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Microphone ( Edison type )
Materials:

Binchotan

leading cords

electric battery

battery case

cassette tape recorder

Preparation:

1. Crossing two pieces of Binchotan on a box of cardboard, you connect them with an electric cell by leading cords.
2. After connecting the ends of both Binchotans by leading cords with microphone terminal of a tape recorder, you switch on the circuit.

How to use:

1. Please speak to the box , recording by the tape recorder. Because of the vibration of the box the electric resistance between both pieces of charcoals changes. Then we can get electric signals as change of voltage.
2. You make sure of the recorded voice playing it back. Could you record your voice ?

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