Generator effect: a voltage is induced in a conductor/ coil when it moves through a magnetic field or when a magnetic field changes through it.
Generator effect in lab: move the conductor in a fixed magnetic field or move a magnetic field relative to a fixed conductor.
Generator effect in large scale (alternators): as a coil rotates, it cuts field lines. This induces a potential difference causing a current.
Dynamos are the same as alternators except there is a split-ring commutator.
Factors affecting size of induced p.d: speed of wire, coil or magnet, number of turns on the coils of wire, size of the coils, strength of the magnetic field.
Factors affecting direction of induced p.d: poles of the magnet.
Microphones: sound waves cause vibrations inside the microphone, so the coil moves and cuts the magnetic field, inducing potential difference, causing current.
Loudspeakers and headphones: a current-carrying wire has a magnetic field. This interacts with the permenant magnet and this causes a force. As the magnetic field is constantly changing direction, the force exerted on the coil will constantly change direction, so coil oscillates.
Tranformers: an alterating current has a constantly changing magnetic field which induces a potential difference causing a current.
Transformers can change the size of an alternating voltage.
Step-up transformers: P=IV means we want to keep current really low to reduce unwanted heat energy lost, so we use a high voltage.