Transformers
- Created by: Sophie
- Created on: 05-05-13 11:21
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- Transformers
- Change the p.d- but only AC p.d
- Primary and secondary coils, joined with an iron core
- Step-up transformers
- Increase voltage
- More turns on the secondary coil than the primary coil
- Magnetic field in the iron core
- Step-down transformers
- Decrease voltage
- More turns in the primary coil than secondary
- Work by electromagnetic induction
- Primary coil produces a magnetic field which stays within the iron core. So neraly all of it passes through the secondary coil and hardly any is lost
- Alternating current in the primary coil means the field in the iron core is constantly changing direction- its a changing magnetic field
- Rapidly changing magnetic field felt by the secondary coil
- Changing field induces an alternating potential difference across the secondary coil
- Electromagnetic induction of a potential difference
- Relative number of turns of the two coils deterines whether the p.d in the secondary coil is less or greater than the p.d in the primary
- Step-up = p.d in secondary coil is larger than p.d of primary
- Step-down transformer = the p.d across the secondary coil is less than the p.d of primary
- Changing field induces an alternating potential difference across the secondary coil
- Rapidly changing magnetic field felt by the secondary coil
- Alternating current in the primary coil means the field in the iron core is constantly changing direction- its a changing magnetic field
- Primary coil produces a magnetic field which stays within the iron core. So neraly all of it passes through the secondary coil and hardly any is lost
- DC wouldn't work as although there'd be a magnetic field in the core, it wouldn't be constantly changing so there'd be no induction in the secondary because you need a changing field to induce a p.d.
- Iron ncore is for changing the magnetic field; no electricity flow through it.
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