BRAINCAKEElectromagnetic Induction
Revision notes for Electromagnetic Induction in OCR Physics A (H556). 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 and 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.