Magnet through Pipe Experiment, continued

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Discussion Overview

The discussion revolves around the effects of a falling magnet through a pipe, specifically focusing on the induced currents and their implications on momentum. Participants explore the relationship between the magnet's descent, the induced currents, and the forces acting on the pipe, touching on both classical and quantum physics concepts.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • One participant suggests that the induced currents from the falling magnet slow its descent and questions how the momentum of these currents is dissipated after the magnet exits the pipe.
  • Another participant asserts that the pipe experiences a downward force due to the induced currents, proposing that an external upward force is necessary to prevent the pipe from moving.
  • A similar point is reiterated regarding the need for an upward force on the pipe, linking it to the momentum carried by the induced currents and comparing the situation to interrupting a DC current.
  • One participant introduces the idea that the discussion may involve quantum physics when considering electron momentum.
  • Another participant counters that quantum mechanics is not necessary for this scenario, arguing that classical electrodynamics sufficiently describes the behavior of bulk currents and matter.
  • A later reply clarifies that the momentum referred to in the earlier post pertains to the electrons, not the magnet, suggesting a quantum physics perspective for that aspect.

Areas of Agreement / Disagreement

Participants express differing views on whether quantum mechanics is relevant to the discussion, with some arguing for its necessity while others maintain that classical physics suffices. The discussion remains unresolved regarding the implications of momentum and the forces involved.

Contextual Notes

There are unresolved assumptions regarding the nature of the forces acting on the pipe and the treatment of momentum in the context of classical versus quantum physics. The discussion also reflects varying interpretations of the relationship between the magnet and the induced currents.

Samson4
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The changing magnetic field of a falling magnet induces currents in the pipe that slows it's fall through the pipe.

Question:
If the induced currents are decreasing the magnets descent then they must themselves have momentum. How is it dissipated once the magnet has passed through the end of the pipe? Does it simply oscillate similar to an lc circuit?
 
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The pipe in which current take place undertakes force downward. One should apply upward force from outside so that it does not move.
 
anuttarasammyak said:
The pipe in which current take place undertakes force downward. One should apply upward force from outside so that it does not move.
That applied force increases the momentum that is carried in the currents induced by the magnet. If they were both free falling then technically it would be the same as them being stationary. I'm asking if the magnet exciting the pipe is similar to interrupting dc current.
 
I think we're in the realm of quantum physics when we deal with electron momentum.
 
rude man said:
I think we're in the realm of quantum physics when we deal with electron momentum.
There's no quantum mechanics required for this problem - we're working with bulk currents and properties of matter that are adequately described by classical electrodynamics.
 
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Quoting the OP: "That applied force increases the momentum that is carried in the currents induced by the magnet."

Clearly he was referring to the momentum carried by the electrons, not the magnet. It's a subject for quantum physics.
 

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