Induced potential and transformers — WJEC GCSE Physics
In summary: Induced potential and transformers is a key topic in WJEC GCSE Physics. Key exam tip: Always check if the question asks for the relationship between turns and voltage or the relationship between primary and secondary power.
Exam Tips for Induced potential and transformers
- Always check if the question asks for the relationship between turns and voltage or the relationship between primary and secondary power.
- Remember that transformers require a changing magnetic field, which is why they do not work with direct current.
- Use the transformer equations carefully, ensuring consistent units for potential difference and current.
Common Mistakes
- Confusing the direction of induced current with the original magnetic field change.
- Incorrectly applying the transformer equation by swapping primary and secondary values.
- Failing to recognize that transformers only operate with alternating current.
- Assuming power is lost in an ideal transformer calculation.
Marking Points
- Induced potential difference is generated by a change in the magnetic field through a coil.
- The induced current generates a magnetic field that opposes the original change.
- Alternators generate a.c. and dynamos generate d.c.
- Factors affecting output potential difference include coil turns, magnetic field strength, and rate of rotation.
- Transformers use alternating current to induce a potential difference in a secondary circuit.
- The ratio of potential differences across coils is equal to the ratio of the number of turns in each coil.
- The relationship V1I1 = V2I2 applies to ideal transformers.
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