Download Scientists used models to help them understand a process. Each

MODELS OF ELECTRICITY
Scientists used models to help them understand a process. Each part
of the model represents something in real life. A good model fits with
the facts. You are going to compare the ‘coal truck model’ and the
‘supermarket’ model of electricity and decide which one you think is
best.
Facts about electricity
 Electricity carries energy to make things work. This flow of energy is
called an electric current.
 You need a complete circuit to transfer energy from a battery to
make a lamp light.
 The current is the same on both sides of the lamp.
 There is a voltage (change in energy) across any part of a circuit
where energy is entering or where energy is exiting the circuit.
The coal truck model
This model shows a coal
mine and a power station.
There is a single-track
railway between the mine
and the power station.
Coal trucks run along the
railway. The coal trucks
can move quickly or
slowly along the track.
At the coal mine, the coal
trucks are filled with coal.
The coal trucks run along
the tracks and deliver the
coal to the power station.
The empty coal trucks
then return to the coal
mine to be filled with coal
again.
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Read the description of the ‘coal truck’ model carefully and study the
diagram. Then answer the following questions:
1. In the ‘coal truck’ model, what represents:
(i)
the circuit?
___________________
(ii)
the battery?
___________________
(iii) the lamp?
___________________
(iv) the energy?
___________________
2. The moving trucks represent the current. When the truck speeds
up, does the current increase or decrease?
_______________________________________________________________
3. Do you think there is anything in the model about voltage?
Explain your answer.
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
Extension task
4. Do you think this is a good model? Explain your answer.
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
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The supermarket model
Imagine that a new supermarket has just opened and it is so busy that
a special system of delivering bread from the nearby bakery has been
set up with a chain of delivery vans.
Complete the ‘cut and stick’ exercise and then fill in the blanks on the
passage about the ‘supermarket’ model.
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Supermarkets and electric circuits
1. The bakery is like the _______________ in the circuit.
2. The vans are like the _______________ in the circuit.
3. The bread the vans are carrying is like the _______________ carried
by the _______________ in the wire.
4. The supermarket is like the _______________. Here the bread is
passed onto the customers just like the _______________ carried by
the charge is transferred to _______________ energy and
_______________ energy in the bulb.
5. The empty vans return to the bakery for more bread. This is the
same as the _______________ going back to the _______________ for
more _______________.
6. If the bakery manager speeds up the vans leaving the bakery,
bread arrives quicker at the supermarket. This is like
_______________ arriving more quickly at the _______________ in the
circuit.
7. If the bakery manager loads more bread onto each van, then
more bread is delivered to the supermarket in a certain time. This
is like more _______________ being delivered to the
_______________ in a certain time in the circuit.
8. The chain of moving vans is like a flow of _______________. In a
circuit we call this an _______________ _______________.
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Electric circuit model
Study the diagram of the ‘electric circuit’ model below and then with your partner, compare it to both the
‘coal truck’ model and the ‘supermarket’ model.
 Which was the better model for you, the ‘coal truck’ model or the ‘supermarket’ model? Explain your
answer.
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