GCSE›AQA GCSE Physics›Mind mapsElectromagnetismAQA GCSE Physics: Mind mapStudy pack PDFAlso for this subtopic:Revision notesFlashcardsSubtopic testCover factsField round a wireCurrent in a wire makes a magnetic fieldField forms concentric circles around the wireReverse the current and the field reversesStronger with more current, weaker further awaySolenoidA solenoid is a wire wound into a coilLoop fields add together, so field is much strongerField looks like a bar magnet with N and S endsIron core plus solenoid makes an electromagnetElectromagnet can be switched off by stopping currentMotor effectCurrent-carrying conductor in a field feels a forceReverse the current or field and force reversesFleming's left hand: First finger = FieldseCond finger = Current, THumb = ThrustElectromagnetismmagnetism from currentF=BIlF=BIlF=BIlTAmForce calculationF=BIlF = BIlF=BIlB in tesla, I in amperes, l in metresForce is greatest at right angles to the fieldForce is zero when the wire is parallel to the fieldDoubling the current doubles the forceDevicesBell, relay and lock: current makes a coil attract ironLoudspeaker: varying current makes coil and cone vibrateVibrating cone creates sound at the same frequencyExam tipsTrace the chain: current, field, attraction, movementUse the left hand for the motor effectScrapyard crane: current off drops the load