Yr11 Electrical Power 13'8

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Yr11 Electrical Power 13.8

• Revision

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Water flows in a river Current how much water
flows in a certain time Current the rate of
flow of water
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Charge flows in an electrical circuit Current
how much charge flows in a certain time Current
the rate of flow of charge
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Charge is given electrical energy by the power
supply
The charge loses energy when it flows through
components in the circuit. When it flows through
a resistor it changes to heat energy.
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The power of a device or component I how quickly
it transfers energy
Put these 4 devices in order of increasing power
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1. How much heat energy does a 3kW kettle produce
in 2 minutes? P 3,000W t 120s So E.T. P
x t 3,600,000J
2. An electric fire produces 500,000J of heat
energy in 3 minutes. Calculate its power.
3. How long will it take a 2kW water heater to
give 300,000J of heat energy to the water inside
it?
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• A current of 0.5A flows through a 240V bulb.
  Calculate its power.
• C 0.5A V 240V
• P V x C 240 x 0.5 120W

2. What current flows through a 60W, 240V bedside
lamp? 3. Which of these fuses should be used
inside its plug? 1A 5A 10A 15A 30A
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Higher Tier Only