basic transformer
- consists of a primary coil and a secondary coil wound on an iron core
why is iron used?
it is easily magnestised
what does the ratio of the potential differences across the primary and secondary coils of a transformer V p and V s depend on
the ratio of the number of turns on each coil, n p and n s
step up / down potential difference relationship
- up: pd secondary is greater than pd primary, secondary coil has more turns than priamry coil
- down: pd primary is greater than pd secondary
what would happen if transformers were 100% efficient?
the electrical power output would equal the electrical power input, due to same number of turns on each coil so pd is same in each coil
what is primary coil connected to?
an alternating current
what happens as current flows through primary coil?
it generates a changing magnetic field which is transmitted along the iron core and passes through the secondary coil, inducing a pd
iron core function
increases strength of magnetic field
why do transformers only work with ac
- we need a changing magnetic field to induce a potential difference
- dc produces a constant magnetic field so doesn’t work in transformers
step up
- more turns in secondary coil than primary coil
- so pd induced in secondary coil greater than pd induced in primary coil
- steps up pd
step down
- more turns in primary coil than secondary coil
- so pd induced in primary coil greater than pd induced in secondary coil
- steps down pd
