1. Models

2. Central heating model
boiler and pump
radiator

3. Central heating model
The boiler transfers heat energy to the water, and a pump pushes the water through the pipes.
boiler and pump
A cell transfers energy to the electrons and pushes them through the wires.
radiator

4. Central heating model The pipes let hot water flow through them.
boiler and pump
Wires are good conductors and let electrons flow through them.
radiator

5. Central heating model
radiator
boiler and pump
In the radiator, heat energy is transferred from the hot water to the room.
In a bulb, electrical energy is transferred to the room as light and heat energy.

6. Central heating model
All the water stays in the pipes. If you measure the amount of water flowing you would get the same reading at A and B. The water at B would have less heat energy than the water at A. A B
radiator
boiler and pump
All the electrons stay in the wires. If you measured the current (the amount of electricity flowing) each side of a bulb would get the same reading. The current transfers energy as it goes through the bulb.

7. The obstacle race model
7Jb
Which team do you think will win?

8. The obstacle race model
7Hd
7Jb
Electrical dangers
The red team will because they did not have to climb over the nets.
This model can help us think about resistance.
The red team’s track had a lower resistance than the blue team’s track.

9. The obstacle race model
7Hd
7Jb
Which team do you think will win?
Which team’s track has the highest resistance?

10. The obstacle race model
7Hd
7Jb
Which team do you think will win?
The yellow team will win, because their net is easier to climb over.
The yellow team’s track had a lower resistance than the blue team’s track.

11. The obstacle race model
7Hd
7Jb
Which team do you think will win?
Why do you think this will happen?

12. The obstacle race model
7Jb
Electrical dangers
The green team will win.
They can reach the end of the track faster because there are two different nets. Each runner only has to climb one net.
The green team’s track had a lower resistance than the red team’s track.

13. How good are models?
A model is a way of helping us to think about things that can be hard to understand.
Some models are better than others.
Which is the best model to help you think about electricity in a circuit?

14. How good are models? A current is electrons flowing around a circuit.
Central heating model:
The flow of water models the flow of electrons.
Obstacle race model:
The competitors model the electrons.

15. How good are models?
The electrons carry energy around the circuit. The energy is transferred to the surroundings as it flows through components.
Central heating model:
Heat energy is carried by the water. The heat energy is transferred to the room as the water flows through the radiator.
Obstacle race model:
The competitors are using energy stored in their bodies. They get hot, so some energy is transferred to the surroundings.
The obstacle race does not model energy transfer well.

16. How good are models?
Components have resistance, which makes it difficult for electricity to flow through them.
Central heating model:
Water can flow easily through all the pipes. The central heating system does not model resistance very well.
Obstacle race model:
The scramblings nets model resistors. The higher the net, the harder it is for the competitors to get over it. This is a god model for the way a resistor affects the current in a circuit.

17. How good are models?
Current can flow along different paths in a parallel circuit.
Central heating model:
This model only has one loop of pipes for the water to flow through.
How could you change the model to represent a parallel circuit?
Obstacle race model:
The competitors finish the race faster if there are two parallel ‘resistors’ for them to climb over. This is a good model of resistors (or bulbs) in parallel.