Exam-style question
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Explain how a generator converts mechanical energy into electrical energy, describing the role of changing magnetic flux and Lenz's law.
Model answer
What a good answer should say
- A generator converts mechanical energy into electrical energy by rotating a coil within a magnetic field, which changes the magnetic flux through the coil.
- According to Faraday's law, this changing flux induces an electromotive force (emf) in the coil.
- Lenz's law states that the induced emf creates a current whose magnetic field opposes the change in flux, ensuring energy conservation.
- The resulting current can be extracted as useful electrical power.
Explanation
Why this works
The answer demonstrates an understanding of Faraday's law and Lenz's law, linking mechanical motion to induced emf and the direction of induced current. It tests the student's ability to explain the physical mechanism of induction in a generator and to articulate the role of changing flux and opposition to change.
Common mistake
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