A copper ring is held horizontally and a bar magnet is dropped through the ring with its length along the axis of the ring. The acceleration of the falling magnet is:
Correct answer: B. Less than that due to gravity
- A. Equal to that due to gravity
- B. Less than that due to gravity
- C. More than that due to gravity
- D. Depends on the diameter of the ring and the length of the magnet
Explanation
The explanation is: When a bar magnet is dropped through a copper ring with its length along the axis of the ring, it induces eddy currents in the ring. These eddy currents create a magnetic field that opposes the motion of the falling magnet due to Lenz's law. As a result, the falling magnet experiences a magnetic damping force. This magnetic damping force acts against the force of gravity, and it effectively reduces the acceleration of the falling magnet. The magnet is not in free fall because it is experiencing this additional magnetic force, making its acceleration less than that due to gravity. So, option b is the correct answer. The acceleration of the falling magnet is less than that due to gravity due to the opposing magnetic force generated by the ring.
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About Electromagnetic Induction
Changing magnetic flux induces an emf according to Faraday's law, while Lenz's law gives the direction that opposes the change producing it. Transformers apply induction between coils to step alternating voltage up or down, with turns ratio, current transformation and energy losses determining practical operation.
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