GCSE›Edexcel GCSE Physics›Mind mapsComponents in Series & Parallel CircuitsEdexcel GCSE Physics: Mind mapStudy pack PDFAlso for this subtopic:Revision notesFlashcardsSubtopic testCover factsTest circuitCell, ammeter and component in one loopAmmeter in series with the componentVoltmeter in parallel across itVary the variable resistor and record readingsFixed resistorCurrent directly proportional to p.d.At constant temperatureResistance stays constantFilament lampFilament heats up as current risesIts resistance increasesCurrent rises less than proportionallyCircuit componentstesting in circuitsLDRLEDDiodeCurrent flows in one direction onlyForward: very low resistanceReverse: very high resistanceAlmost no current in reverseLDR and thermistorLDR: more light → resistance fallsThermistor: hotter → resistance fallsResistance from R=VIR = \frac{V}{I}R=IVMore stimulus, less resistanceExam tipsLamp resistance is not constant, not 'ignores the rules'Cause: temperature changes with current