- #1
How Does Lenz's Law Relate to Magnetic Flux and Induced Currents?
- Context: Undergrad
- Thread starter rayjbryant
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- Electrcity Law Lenz's law Magnetism
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Discussion Overview
The discussion revolves around the relationship between Lenz's law, magnetic flux, and induced currents, particularly in the context of two magnets with like poles facing each other moving through a copper coil. Participants explore the implications of this setup on the behavior of induced currents and magnetic flux changes.
Discussion Character
- Exploratory
- Technical explanation
- Debate/contested
Main Points Raised
- One participant asserts that Lenz's law is always obeyed, suggesting that the induced current will always act to resist the motion of the magnets, implying that perpetual motion is impossible.
- Another participant questions whether there would be a net current in one direction due to the greater flux density of the South poles when they face each other.
- A different participant argues that the flux between the two South poles is the sum of the flux due to each pole, implying that there would not be a net current in one direction.
- One participant prompts a consideration of whether there is any change in magnetic flux through the coil as the magnets move, indicating that this is a critical factor in understanding the induced currents.
- Another participant suggests a mathematical approach to understanding the flux change, referencing an integral that relates to the change in function values, hinting at the importance of initial and final conditions of flux.
Areas of Agreement / Disagreement
Participants express differing views on the effects of the magnetic setup on induced currents, with some suggesting that Lenz's law will always apply while others question the specifics of flux changes and net current direction. The discussion remains unresolved with multiple competing views present.
Contextual Notes
There are assumptions regarding the distance of the magnets from the coil and the initial and final states of magnetic flux that are not fully explored. The implications of these assumptions on the induced currents are not settled.
- #2
rude man
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Lenz's law is always obeyed. Otherwise you'D HAVE A PERPETUAL-MOTION MACHINE. tHERE IS NO FREE LUNCH.rayjbryant said:
iN YOUR CASE THE CURRENT THRU THE COIL WOULD FIRST GO ONE WAY, THEN THE OTHER, ALWAYS SUCH AS TO RESIST THE MAGNETS' MOTION.
- #3
rayjbryant
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Would there be a net current in one direction do to greater flux density of the South poles?
- #4
Herman Trivilino
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Because the two south poles face each other? No, because the flux between the two south poles is the sum of the flux due to each south pole.rayjbryant said:
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rayjbryant said:
I will ask you this: Is there any magnetic flux change through the coil as the magnets move through it?
Zz.
- #6
rude man
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Good question.
Assuming the magnets are far away from the coil, move into then out of the coil in the opposite (could also be in the same) direction so the flux is initially and finally zero, then my hint is what you undoubtedly already know:
## \int_a^b f'(x) \, dx = f(b) - f(a) ##
Assuming the magnets are far away from the coil, move into then out of the coil in the opposite (could also be in the same) direction so the flux is initially and finally zero, then my hint is what you undoubtedly already know:
## \int_a^b f'(x) \, dx = f(b) - f(a) ##
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