Contents
Key Stage 4
Meaning
An alternating current is an electrical current which changes direction.
About Alternating Currents
- Alternating currents are caused by alternating potential differences.
- Alternating currents have a frequency at which they alternate.
- Mains electricity is an alternating current working at a frequency of 50Hz, so the current changes direction 50 times every second.
- Alternating currents cannot be used to charge a cell or battery.
- Alternating currents cannot be used in electrolysis.
- Alternating currents are used in transformers.
Examples
 |
| An oscilloscope trace of mains electricity shows its frequency is 50Hz as the time period is 0.02s per oscillation and the peak potential difference is 320V, but the average over time is 230V. |
References
AQA
- Alternating current (a.c.), page 305, GCSE Combined Science Trilogy 1, Hodder, AQA'
- Alternating current (a.c.), page 50, GCSE Physics, Hodder, AQA'
- Alternating current (a.c.), pages 46, 66, GCSE Physics; Student Book, Collins, AQA'
- Alternating current, pages 64-65, 224-229, GCSE Physics; Third Edition, Oxford University Press, AQA'
- Alternating currents (a.c), page 188, GCSE Combined Science; The Revision Guide, CGP, AQA'
- Alternating currents (ac), pages 31, 96, 97, GCSE Physics; The Revision Guide, CGP, AQA'
- Alternating currents (ac), pages 86, 203, GCSE Combined Science Trilogy; Physics, CGP, AQA'
- Alternating currents (ac), pages 89, 245, 306, GCSE Physics; The Complete 9-1 Course for AQA, CGP, AQA'