The cell and Battery

1. The cell and Battery

2. The electrons are always in the wire and it is the cell which makes them move. • In the cell there is a chemical reaction which creates and maintains an imbalance of the spread of electrons with more of them on the sides than in the centre.This imbalance causes the cell to push and pull at the same time.

3. This movement or drift of electrons creates an even spread of electrons in the cell. • The cell then works to try to re-establish the imbalance. This is done by the chemical reaction • The electrons move from the negative end of the cell to the positive end.This is like a lot of things in electricity contrary to what most people would think.

4. Positive/negative • The electrons are always in the wire and it is the cell which makes them move. • In the cell there is a chemical reaction which creates and maintains an imbalance of the spread of electrons with more of them on the sides than in the centre. This imbalance causes the cell to push and pull at the same time.

5. Two cells • The push and pull of a cell is the voltage of it.  A battery is made up of several cells all pushing and pulling. • The more the voltage the greater the pushes and pulls. • All the pushes and pulls must also be in the same direction if a number of cells are going to work effectively

6. 3 cells  and amps • A 4.5 Volt battery has three cells and it will have an even bigger push and can therefore push more electrons through the wire. • The number of electrons being pushed through a wire is called the currentand the current is usually measured in amperes (A). • Remember the movement of electrons can best be described as a drift as it is not very fast.

7. Conduct / Insulate • Most non-metallic materials contain atoms which have nofree electrons so a battery or cell cannot persuade them to move. These materials are called insulators. Metals are in a group of materials called conductors. • The wires that are used are covered with a plastic material. This is an insulator. Air is quite a good insulator so you will not get electricity leaking out of plugs, or batteries.

9. Symbols 1 • Instead of drawing the components of a circuit we can represent them by symbols.

10. Switches • This is how the symbols fit together to make a circuit diagram. • The bulb and battery symbols are joined by solid black lines with right angle bends. This represents the wire

11. Switches • As well as a simple on/off switch there are also push switches and two way switches available. • A normally-open push switch will only let electricity pass when it is held down. • A normally-closed push switch will let electricity flow until the switch is pushed. • The two-way switch lets electricity flow along either one path or another.

12. 2 bulbs in a circuit • If you connect one battery (1.5 volts) to one bulb (1.5 volts) the bulb lights up quite brightly. • What do you think happens if you connect two 1.5 volt bulbs to one battery?

13. In this circuit the two light bulbs are sharing the "push" of one cell. • The bulbs are very dim. What happens when one of the bulbs breaks? • This type of circuit is called a series circuit

16. A parallel circuit • Another way of arranging two light bulbs is like this. • In this arrangement, each bulb experiences the push of the cell directly. • This is called a parallel circuit. • If each bulb is the same brightness it must have the same electric current flowing through it.

17. A parallel circuit • This type of circuit is called a parallel circuit. • Take out any one light bulb and only it goes out. The others remain the same brightness.

18. Electricity in the House • A parallel ring circuit is used in the house. All the lights get a 240 volt push. • Switching off one bulb doesn't make all the lights in the house go out. • The picture opposite is an example of a ring parallel circuit.