OpenRevise GCSE

Physics · Paper 1

Electricity

Circuit symbols, charge and current, resistance and I-V characteristics, series and parallel circuits, mains electricity and safety, power and energy transfers, the National Grid, static charge and electric fields.

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Key terms in this chapter

All 60, gathered from every lesson.

Electric current
The rate of flow of electrical charge.
Charge
A property of matter that can be positive or negative; measured in coulombs.
Ampere
The unit of current; one coulomb per second.
Coulomb
The unit of charge.
Ammeter
Measures current; connected in series.
Potential difference
The energy transferred per unit of charge; measured in volts.
Series
Components connected one after another in a single loop.
Parallel
Components connected on separate branches.
Equivalent resistance
The single resistance that could replace the combination.
Branch
One of the paths in a parallel circuit.
Total resistance
The resistance of the whole circuit.
Shared pd
The supply pd divides between series components.
Direct pd (dc)
A pd that always pushes charge in the same direction.
Alternating pd (ac)
A pd that repeatedly changes direction.
Frequency
The number of cycles per second, in hertz.
Live wire
The wire carrying the alternating pd, at about 230 V.
Neutral wire
The wire that completes the circuit, at about 0 V.
Earth wire
The safety wire, at 0 V, connected to the metal case.
Power
The rate at which energy is transferred.
Watt
One joule per second.
Power rating
The power an appliance transfers in normal use.
Kilowatt
1000 watts.
Potential difference
Energy transferred per coulomb of charge.
Current
The rate of flow of charge.
Electrical work
Energy transferred when charge flows in a circuit.
Power rating
The power of an appliance in normal use.
Appliance
A device that transfers electrical energy usefully.
Kinetic store
The energy of a moving object.
Thermal store
The energy of hot objects.
Charge
Measured in coulombs.
National Grid
A system of cables and transformers linking power stations to consumers.
Transformer
A device that changes the size of an alternating pd.
Step-up transformer
Increases the pd.
Step-down transformer
Decreases the pd.
Transmission cables
Cables that carry electricity over long distances.
Efficient
Wasting little energy.
Static electricity
Charge that builds up on an insulator.
Electron
A negatively charged particle.
Non-contact force
A force between objects that are not touching.
Earthing
Connecting to the ground so charge can flow away.
Repel
Push apart.
Attract
Pull together.
Electric field
The region around a charged object where another charge feels a force.
Field lines
Lines showing the direction of the force on a positive charge.
Isolated sphere
A charged sphere far from any other charges.
Ionise
Remove or add electrons to make ions.
Non-contact force
A force between objects that are not touching.
Field strength
How large the force on a charge is at a point.
Resistance
How much a component opposes the flow of current.
Ohm
The unit of resistance (Ω).
Potential difference
The energy transferred per coulomb; measured in volts.
Voltmeter
Measures pd; connected in parallel.
Constant temperature
Kept the same so the resistance does not change for other reasons.
Directly proportional
Doubling one quantity doubles the other.
Ohmic conductor
A conductor whose resistance is constant at constant temperature.
Filament lamp
A lamp with a thin wire that gets hot and glows.
Diode
A component that lets current flow in one direction only.
Thermistor
A resistor whose resistance decreases when the temperature increases.
LDR
A resistor whose resistance decreases when the light intensity increases.
Linear
Following a straight line graph.