Current Electricity

The first battery (or cell) was discovered by Luigi Galvani. He was dissecting a frog at the time. He happened to be using two dissecting tools each of different metals. He touched a nerve and the dead frog's leg twitched! He had accidentally produced an electric current. This lead to the development of what we now call the battery. To be pedantic, the correct name is a cell and a battery is really the name given to a collection of several cells joined together to produce a higher voltage.

A cell can be made from a lemon:

It requires a very sensitive ammeter to detect this current. This will not produce a sufficient current or voltage to light a bulb or, in fact, do anything very useful!

 

Making a bulb light

It can be discovered that the following criteria need to be met:

  • A complete circuit with no gaps
  • Both ends of the battery must be connected within the loop
  • The circuit must be joined by conductors

N.B. It is far more useful for children to discover how to make a bulb light for themselves, rather than be shown how to do it.

 

Models

The flow of electricity can be compared to a flow of water through a pipe.

It is, of course, important to realise the limitations of this model, e.g. nothing leaks out of the wire if it is cut!

An electric current is a flow of electrons. The battery gives the electrons energy which results in this current. But what are electrons?

Contents

Safety, Static Electricity
Charge
Atomic Theory
Conductors and insulators
Switches, Short circuits, Circuit diagrams
Current, Voltage
Electrical circuits
Measuring current
Resistance
Power
Assessment/Discussion Material
Reference Material