Click here to go back to previous page

Conductor - materials that let electric current flow through them are called conductors. Metals, such as copper and aluminium, are good conductors. Some materials, such as rubber and paper, are bad conductors and are used as insulators to prevent a flow of electricity.

Constant - any amount in maths or physics that does not vary. For example, pi is a constant that describes the relationship between the circumference and the diameter of any circle.

Efficiency of a machine - how the energy which the machine produces relates to the energy put into it. In Victorian times, many people were trying to make steam engines do more work for a given amount of heat supplied by the coal.

Energy - if an object has energy of any sort it is capable of doing work. An engine uses the energy in its fuel to move a car along. Energy is measured in joules (abbreviated to J). For larger amounts of energy, kiloJoules (kJ) or megaJoules (MJ) are used. Energy cannot be made or destroyed, but can be converted from one sort to another.

Force - force is the word we use for a push or a pull. It can make something move or move faster, more slowly or in a different direction. Force is measured in Newton's. It makes a force of about five Newton's to switch on a light and about 20 to open a canned drink.

Friction - this is the force which tries to stop one material sliding over another. If you push a toy on a carpet, it cannot keep going for long because it rubs against the carpet. Rough things make more friction than smooth things.

Molecules - the smallest bit of water you can have is a molecule of water. It is made up of two hydrogen atoms joined to one oxygen atom. The simplest molecules contain just two or three atoms, sometimes of the same element. Atoms themselves are made up of sub-atomic particles called protons, neutrons and electrons.

Work - work is done whenever a force makes something move. The greater the force, and the further it moves, the more work is done. It is hard work pedalling uphill or moving heavy objects about. Work is measured in joules.

Click here to go back to previous page