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Energy transferred (in an electrical circuit) =
power x time
What forces electrons round a circuit?
work done by the power supply
The current through an electrical appliance is:
the charge that flows through it each second
The potential difference across an electrical appliance is:
the energy transferred to the appliance by each coulomb of charge that passes through it
The power supplied to an electrical appliance is:
the energy transferred to it each second
Power supplied =
current x potential difference
How should you choose a fuse?
choose one that is over the normal operating potential difference of the appliance
power = current² x resis
current² x resistance
The power supplied to a resistor is proportional to...
the square of the current
Charge flow =
current x time
Why does a resistor get hotter? [5]
- electrons are pushed round the circuit
- they bump into metal ions in the resistor
- this causes the ions to gain kinetic energy
- they vibrate
- the resistor gets hotter
A resistor becomes hotter when:
charge flows through the resistor, transferring energy to it
Coulomb
unit of charge
The energy supplied to an appliance depends on... [2]
- how long it has been switched on
- the power supplied to it
Efficiency values can be expressed as [2]:
- ratio
- percentage
Why do electrical appliances waste energy? [2]
- the heating effect of current in wires and components
- friction causes heating in appliances with moving parts
Note 
Flashcard (49)