Using hookup wire and crocodile clips connect the two terminals of the DC micro ammeter to the two plates. The DC micro ammeter is used to measure electric current in a closed circuit. It is available in any local electrical shop.Now mount each of your hand on both the plates.
We will see that the ammeter shows deflection. If it does not show any reading then reassemble by reversing the connection. If it still doesn’t show any deflection then plates need to be cleaned.Now drench both hands and place again on the metal plates. Is there any difference in the meter reading? If so is it more than what we got with dry hand?
We see that there is slight deflection in the ammeter reading. The reason is because there is a thin film of sweat in our hands and the same acts as acid like in a battery. This results in a chemical reaction with both the plates- the copper and aluminum plate. In the process our hand gets negatively charged by taking a negatively charged subatomic particle (electron) from copper.
The aluminum metal on the other hand gets negatively charged as an electron is donated by the other hand to the aluminum metal plate. This difference in charge (also known as potential difference) results in an electric current which is shown by deflection in the ammeter.
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