This activity shows that humans are able to conduct electricity. This is why it is very important to know how to use electricity safely.

Which metals do you need to hold to produce the most electricity?

Does it make a difference if your hands are very dry or quite damp as to how much electricity you can produce?

 

This activity works in a similar way to a chemical battery. When you hold one metal rod in each hand electricity flows through your body. Placing your hands on the metal plates causes the effect of a battery charge. Your hands contain a thin film of sweat that produces a chemical reaction similar to battery acid when placed on the metal plates. Your hands take negatively charged electrons away from the copper plate and transfer them to the aluminium plate, causing it to be negatively charged. The variance in charges between the places produces an electrical current which flows through your body and displays on the meter. 
This activity works well with children with damp hands and a reading can be seen on the scale.  When the human's hands are wet, the reading on the current meter is higher than when the hands were not wet. The human body resists the flow of current through the skin. When wet hands are placed on the plates, the resistance to current is decreased thus increasing the flow of current and creating a higher result on the meter.

It is a good activity for investigation. A discussion about the effect of the different metals, does it matter whether you have damp or dry hands, what would happen if you wore gloves how to make a simple fair test, predictions can all be easily carried out using this exhibit.

Using Electricity

Circuits and Conductors

Changing circuits