Hand Battery

A blue and orange exhibit table with a white and blue information panel at the back. On the top of the table are four metal rectangular pads connected to a voltage meter.
A blue and orange exhibit table with a white and blue information panel at the back. On the top of the table are four metal rectangular pads connected to a voltage meter.

Electric fields can be created when a circuit is closed in a loop formation.

How it works

Touch two metal plates to create an electric field (observed on a meter).

Things to try or ask around the exhibit

  • Put your hands on two metal plates. Does the pointer move on the meter?
  • Which combination of metal plates gives the highest reading?
  • Do the readings differ between different people?

Background

Batteries contain two different metals and a paste called an electrolyte that conducts electricity. If your hands are salty with perspiration, they act like the electrolyte in a battery when you touch the metal plates. Together, you (as an electrolyte) and the metal plates make a battery. When you lift your hands off the metal plates (made of copper and aluminium), you remove the battery’s electrolyte so the battery stops working. When you put your hands on the metal plates to create the battery, it makes a very weak electric current flow in a loop through your body and through the meter.

Finding the science in your world

When batteries 'leak', they release the electrolyte contained inside the battery capsule. Batteries can also leak if they are left inside an appliance that has not been used for long periods of time. These electrolytes tend to be corrosive or poisonous and should not be touched with bare skin.