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Tuesday, May 23, 2017
To use a model to represent electricity
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The circuit diagram shows a series circuit with a motor and a
lamp
It shows 3 positions where the ammeter was connected (with
values shown)
What do you notice about
the current?
Current remains the same
– 1.2A leaves the battery,
and 1.2A returns
Each component in series
receives the same current
(1.2A)
1.2A
+- +-
A
A
M
A
1.2A
1.2A
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Electricity is a difficult topic to explain because you cannot
see it!
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To help explain electricity we can use a model – a model
uses things we understand that work in a similar way to the
things we don’t understand
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Look at the power station
model of electricity – stick
it into your book and
answer the questions
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Battery – the coal mine
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Bulb(s) – the power station
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Electric wires – the tracks
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Electrons – the coal trucks
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Current (flow of electrons) – number of coal trucks
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Voltage (push provided) – how much coal the trucks contain
and the push they are given around the circuit
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Switch – workmen who can break or mend the tracks
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If another bulb is added the current is reduced – the coal trucks
give half their coal to one power station, and give the other
half to the second power station
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If another bulb is added the voltage changes, depending on
the resistance of the bulb – e.g. one power station might take
lots of the truck’s coal (high resistance) leaving just a small
amount of coal for the other power station (lower resistance)
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Model not perfect – only describes series circuits / electrons
don’t really flow around (only their charge passes) etc…
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Your task is to come up with your own model for electricity in
a series and parallel circuit
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Think about how you will represent the cell / switch /bulb /
wires
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How will you model current and voltage?
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E.g. you could do the number of
people entering a football stadium to
watch Arsenal - people represent
electrons; the ticket they carry could
be the energy which they transfer at
the gate; the people always go home
and then get a new ticket etc…