Electromagnetic induction, generators and transformers

Learning objectives

Know that an e.m.f. is induced in a conductor that moves across a magnetic field or is in a changing magnetic field, and describe experiments to demonstrate this

State the factors that affect the size of an induced e.m.f., and at Extended know that the induced e.m.f. opposes the change producing it and use Fleming's right-hand rule to find the direction of the induced current

Describe a simple a.c. generator with a rotating coil or rotating magnet and slip rings with brushes, and sketch and interpret its e.m.f.–time graph in relation to the position of the coil (Extended)

Describe the construction of a basic transformer with primary and secondary coils on a soft-iron core, distinguish step-up from step-down transformers, and use Vp/Vs = Np/Ns

Explain how a transformer works using the changing magnetic field produced by an alternating current in the primary coil, and use IpVp = IsVs for a transformer that is 100% efficient (Extended)

Describe the use of transformers in high-voltage transmission of electricity and state its advantages, and at Extended explain the reduced power loss in the cables using P = I²R