BRAINCAKEElectromagnetic Induction
Revision notes for Electromagnetic Induction in AQA Physics (7408). 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.
- Electromagnetic InductionWhen a wire cuts across the lines of a magnetic field an electromotive force (emf) is induced in the wire.
- Energy TransferWhen a coil is rotated in a magnetic field, the coil cuts the lines of the magnetic field, so an emf is induced in the coil.
- A DynamoA dynamo is an electrical generator that produces a current.
- SolenoidWhen a current is passed through a long coil, a magnetic field is produced in and around it.
- Lenz's LawThe direction of the induced current is always such as to oppose the change that causes a current.
- Faraday's Law of Electromagnetic InductionThe Magnetic flux Φ passing through a given area A is the product of the magnetic field density B and the area it passes through. Φ = BA.
- The Alternating Current GeneratorAn a.c. generator is a rectangular coil that spins in a uniform magnetic field.
- Power Station AlternatorsA power station alternator (a.c. generator) is made of 3 sets of stationary coils (stator) at 120° to each other and a rotor - an electromagnet than…
- Back e.m.f.When a current-carrying coil is place in a magnetic field it rotates due to the motor effect and the area swept out by the coil changes.
- TransformersA transformer consists of two coils wound around the same soft iron core.
- Transformer EfficiencyTransformers are designed to be almost 100% efficient.
- The National GridThe National Grid is a network of transformers and cable which supplies most of the UK with electricity from power stations.