Batteries and moving charges

Whenever electricity is to be used an electric circuit is needed. This circuit provides a conductive path to allow the electrical charges to move as an electric current to carry the electrical potential energy from the power supply through the conductors in the circuit.

It is the moving charges (current) that provides the energy needed for an electrical device to operate, i.e. it is the electric charges (usually electrons) flowing through an electrical device that make it work.

It is the power supply that provides the electrical energy for an electric circuit to operate, and the electric current that flows through the circuit that makes the electrical device work, e.g. makes the light globe light up.

What is the difference between a D cell and an AA cell? 

They both provide the same voltage of about 1.5 V but the electrodes in the D cell are larger and able to produce more charge. This means the D cell will last longer, or is more suitable to use when larger currents are needed.

How batteries work

The opposite charge at the end of the battery means that when a conductive path is supplied by conducting leads and a light globe, the charges are able to flow through the conductors as an electric current. This current flows from one pole of the battery to the other. As the charges go through the light globe they lose their electrical energy as it is converted to light energy (and heat).

Even though the animated diagram stops to show how the chemical reaction  in the battery converting chemical energy into electrical energy replaces charge, the battery keeps working, in a real battery the chemical reaction goes on continually so there is a steady voltage produced between the poles (electrodes). This conversion of chemical energy to electrical energy keeps going until the materials in the battery that create the chemical reaction run out. This is why a battery will eventually run out of power.

In the diagram you can see how the smaller AA battery stops more quickly. With smaller reserves of materials to create the chemical reaction, the reaction stops more quickly in the AA cell than it does in the D cell.

The conducting wires in a circuit offer only a very small resistance to the flow of charge, i.e. they are very good conductors. The electrical device does conduct electricity but its resistance is usually much larger than the conducting wires. As the charges flow through this resistance they lose electrical energy which is converted into another form, e.g. the electrical energy is converted into light energy by a light globe.

To explore more about batteries and how they work visit the interactive learning guide  and download the animation battery voltage.
Do you want to help the environment? Recycle your batteries!

Many batteries contain metals which is a concern to the environment if they are not disposed of correctly. If disposed of incorrectly, the heavy metals can leak into the ground causing soil and water pollution. According to Battery World, 8,000 tonnes of batteries are discarded each year in Australia.

Are all batteries hazardous? No. But they can all be recycled!

  • Normal household batteries (Alkaline) are considered non-hazardous waste and are safe for disposal in the normal waste stream.
  • Laptop batteries (Lithium-Ion) do not contain metallic lithium and are not an environmental risk. Small button lithium batteries are a hazard though and if not recycled or disposed of properly can be a poisonous hazard if swallowed. The batteries can generate a current inside the body, triggering a chemical reaction that can burn a hole through organs such as the oesophagus.
  • Car batteries (Lead Acid & Sealed Lead) are recoverable to 96% and the materials extracted are used in remanufacturing of batteries and plastic moulding.
  • Cordless phone batteries and many cordless power tool batteries (Nickel Cadmium) are considered to be hazardous to the environment.
  • Mobile phone batteries (Nickel-Metal Hydride) are considered environmentally friendly and this type of battery can be recycled.

Remember, if you don't recycle batteries, the resources in them will become scarcer.

Find out where you can recycle batteries.

Electrical cord