The energy delivered by an induced current ultimately comes from
Correct answer: B. the mechanical work done against the opposing force predicted by Lenz's law
- A. the magnetic field, which is used up
- B. the mechanical work done against the opposing force predicted by Lenz's law
- C. nothing, since it is created by induction
- D. the resistance of the circuit
Explanation
Because the induced effect opposes the motion, whoever moves the magnet or turns the generator must do work, and that mechanical work is converted into electrical energy. This is why a bicycle dynamo makes pedalling harder once the lamp is switched on. A magnetic field is not consumed in the process.
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About Lenz's Law
Lenz's law states that the induced current flows in a direction that opposes the change in magnetic flux producing it. Questions connect this rule with Faraday's law, magnetic flux, induced emf and the direction of motion or current, while distinguishing opposition to flux change from opposition to the magnetic field itself.
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