BRAINCAKEElectrical Circuits
Revision notes for Electrical Circuits in Edexcel Physics (8PH0). Read the start of any lesson here, then sign in free for the whole lesson, the R.E.C.I.P.E. recall steps and the quiz.
- Current RuleThe total amount of charge in a circuit does not change.
- Currents in Series CircuitsAny components placed in series where there are no junctions will have the same current through it.
- Currents in Parallel CircuitsWhere there are junctions, the current splits at circuit junctions, but the total current will be the same in order to conserve charge.
- Voltage RuleVoltmeters are placed in parallel with the components when the potential difference across a component is to be measured.
- Voltages in Series CircuitsIf cells are placed in series in the same direction the e.m.f. of the circuit will be the sum of the individual e.m.f.s.
- Voltages in Parallel CircuitsThe voltage across each branch of a parallel section of a circuit (branches connected between the same two junctions) will be the same.
- Resistors in Series and ParallelThe total resistance of resistors placed in series is the sum of the individual resistances.
- Resistors - Combinations Question 1Question A 3.0 Ω resistor is connected in series with a parallel pair made of a 6.0 Ω resistor and a 12 Ω resistor.
- Resistors - Combinations Question 2Question You are given three identical 6.0 Ω resistors.
- Resistors - Combinations Question 3Question A 9.0 V battery of negligible internal resistance is connected to a 2.0 Ω resistor R1 in series with a parallel pair, R2 = 6.0 Ω and R3 =…
- Potential DividerA potential divider circuit splits the potential differences up in proportion to their resistances.
- Sensor CircuitsOne of the resistors in a potential divider circuit could be a thermistor or LDR.
- Internal ResistanceThe resistance of an emf source is called the internal resistance.
- Electrical WorkFor the cell or power source to provide electrical energy to move electrons around the circuit and produce a flow of current, work must be done.
- Electrical PowerPower is the rate at which energy is transferred.
- Power Dissipated By ResistorsAll the electrical power dissipated in a circuit by resistors is in the form of heat energy.
- EfficiencyElectrical energy efficiency is always less than 100% because components and devices waste energy as heat energy.
- Exam Style Question - 1Question An electric motor is connected to a 12 V supply and draws a current of 2.5 A.
- Exam Style Question - 1Question A potential divider consists of a fixed 2.0 kΩ resistor in series with a thermistor, connected to a 6.0 V supply of negligible internal…
- Exam Style Question - 2Question Two heating elements, of resistance 24 Ω and 12 Ω, are connected in parallel to a 12 V supply of negligible internal resistance.
- Exam Style Question - 3Question A car battery has an e.m.f. of 12 V and an internal resistance of 0.020 Ω.
- Exam Style Question - 4Question A student connects a battery to a 4.0 Ω resistor and measures a terminal p.d. of 4.0 V.