Electricity and circuits

Edexcel GCSE Combined ScienceTopic 10 of 1442 lessons

Revision notes for Electricity and circuits in Edexcel Combined Science (1SC0). Every lesson in BrainCake comes with R.E.C.I.P.E. recall steps, a quick check and spaced reviews.

1. Structure of the atomEvery atom has a tiny nucleus at its centre.
2. Circuit diagrams and symbolsA circuit diagram uses standard symbols so that anyone can read it.
3. Series and parallel circuitsIn a series circuit the components are connected one after another in a single loop.
4. Using a voltmeterA voltmeter measures the potential difference, also called the voltage, across a component.
5. Potential difference and energyPotential difference is the energy transferred per unit charge that passes between two points.
6. Energy, charge and potential differenceThe energy transferred depends on how much charge moves and on the potential difference it moves through.
7. Using an ammeter to measure currentAn ammeter is the meter that measures the electric current in a component.
8. Current as a flow of chargeAn electric current is the rate of flow of charge.
9. The charge, current and time equationCurrent is the rate of flow of charge, so the charge, measured in coulombs, that moves depends on the current and on how long it flows.
10. Current in a closed circuitA current is a flow of charge, so something must push the charge round.
11. Current at a junctionIn a series circuit there are no branches, so the current is the same everywhere in the loop.
12. Resistance and the variable resistorResistance is how much a component opposes the flow of charge.
13. Potential difference, current and resistance (V = IR)Resistance tells you how hard it is for charge to flow through a component.
14. Resistors in series and in parallelWhen two resistors are connected in series, all the charge has to pass through the first resistor and then through the second.
15. Calculations in series circuitsIn a series circuit there is only one loop, so the current is the same at every point.
16. Designing series circuits for testing and measuringA circuit for testing a component is built as one series loop: a power supply, a switch, the component under test, an ammeter and, if wanted, a…
17. Core practical: potential difference, current and resistanceAim: to investigate how the current in a fixed resistor and in a filament lamp depends on the potential difference across it.
18. Current and potential difference for resistors, lamps and diodesA fixed resistor has a constant resistance if its temperature stays the same.
19. Resistance of a light-dependent resistor (LDR)A light-dependent resistor (LDR) is a component whose resistance changes with the brightness of the light falling on it.
20. Resistance of a thermistorA thermistor is a resistor whose resistance depends on its temperature.
21. Investigating resistance in circuit devicesTo explore how the resistance of a device changes, we build a circuit and measure the current through the device and the potential difference across…
22. Heating effect of an electric currentWhen there is an electric current in a resistor, the resistor gets hot.
23. Energy dissipated by a current doing work against resistanceWhen a current passes through a component, the charges do work against the resistance of the component.
24. Collisions between electrons and ions in the latticeA metal wire is made of a lattice of positive ions, with free electrons moving between them.
25. Reducing unwanted energy transfer in low resistance wiresConnecting wires have a very small resistance, but it is never zero.
26. Advantages and disadvantages of the heating effectWhen there is a current in a resistor, energy is transferred to heat it.
27. Energy transferred, current, potential difference and timeThe energy transferred by an electric current depends on three things: how large the current is, the potential difference (p.d.) it is driven by…
28. Power as energy transferred per secondPower is the energy transferred per second.
29. Power, energy transferred and time takenPower is the energy transferred divided by the time taken: power = energy transferred ÷ time taken Power is in watts (W), energy transferred in…
30. Power, potential difference and currentThe power of a circuit device depends on the potential difference (p.d.) across it and the current in it.
31. Electrical power: P = IV and P = I²RThe electrical power of a device is the rate at which it transfers energy.
32. Energy transfers in domestic devicesDomestic devices are powered either by a battery or by the a.c. mains.
33. Direct and alternating voltageA potential difference (voltage) pushes charge round a circuit.
34. Direct currentAn electric current is a flow of charge.
35. Alternating currentIn alternating current (a.c.) the movement of charge changes direction.
36. UK mains supplyThe domestic electricity supply in the UK is alternating current (a.c.).
37. Live and neutral wiresThe UK mains supply is alternating current at about 230 V.
38. Earth wire, fuses and circuit breakersMany appliances have a metal case.
39. Switches and fuses in the live wireA switch and a fuse are both connected in the live wire of a domestic circuit.
40. Potential differences of the mains wiresThe UK domestic supply has a potential difference (p.d.) of about 230 V between the live wire and the neutral wire.
41. Dangers of a live to earth connectionConnecting the live wire to earth is dangerous.
42. Power ratings of domestic appliancesThe power rating of an appliance tells you how much energy it transfers each second.

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