Why does a change of magnetic flux induce an EMF?

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Discussion Overview

The discussion revolves around the question of why a change in magnetic flux induces an electromotive force (emf) while a static magnetic field does not. Participants explore the underlying principles, seek intuitive explanations, and consider the relationship between electric and magnetic forces. The conversation includes requests for clarity suitable for a high school level of understanding.

Discussion Character

  • Exploratory
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant questions the rationale behind the induction of emf from changing magnetic flux and seeks an intuitive explanation, emphasizing their status as a high school student.
  • Another participant highlights the difficulty of answering "why" questions without a shared set of assumptions and expresses concern over the exclusion of mathematical explanations and advanced concepts.
  • Some participants propose that the inability to generate emf from a static magnetic field relates to the principle of not getting something for nothing, suggesting that work can only be done with changing fields.
  • There is mention of Maxwell's equations and the derivation of Faraday's law through various accepted frameworks, such as conservation of magnetic flux and relativity.
  • A participant reflects on the nature of physical laws, suggesting that while the "why" may remain elusive, observations can fit into a consistent framework that predicts natural phenomena.
  • References to external resources, such as a video featuring a prominent intellectual, are made to provide additional context or insight into the topic.

Areas of Agreement / Disagreement

Participants express differing views on the nature of explanations and the foundational assumptions required to address the original question. There is no consensus on a definitive answer regarding the induction of emf from changing magnetic flux versus static fields.

Contextual Notes

Participants note limitations in the discussion, particularly regarding the exclusion of mathematical reasoning and advanced concepts that may be necessary for a complete understanding of the topic.

funmi
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How and why does a changing magnetic flux induce an emf? Why doesn't a static one also produce one? How are the electric and magnetic forces related? Why do you move a wire through a magnetic field so that the wire, the motion, and the magnetic field are all mutually orthogonal in order to produce the emf? I want an intuitive explanation please. Also take into consideration that I'm a high school student.
 
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This is going to be a very difficult question to answer. “Why” questions are notoriously difficult to answer. Basically, to answer a “why” question requires that the questioner and the answerer have an agreed upon set of accepted assumptions or background that can be used as explanations.

Unfortunately, you exclude math (not intuitive), explanations by contradiction, and any concepts introduced after high school. I have no idea what explanations are left, what common basis of understanding you will allow. Since you have a priori rejected so much of our usual possible common basis, please spend some time explaining what we can use in an acceptable answer.
 
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Dale said:
This is going to be a very difficult question to answer. “Why” questions are notoriously difficult to answer. Basically, to answer a “why” question requires that the questioner and the answerer have an agreed upon set of accepted assumptions or background that can be used as explanations.

Unfortunately, you exclude math (not intuitive), explanations by contradiction, and any concepts introduced after high school. I have no idea what explanations are left, what common basis of understanding you will allow. Since you have a priori rejected so much of our usual possible common basis, please spend some time explaining what we can use in an acceptable answer.
Please explain as simply as you can, if you reference something I don't understand I'll ask for clarification
 
funmi said:
Please explain as simply as you can, if you reference something I don't understand I'll ask for clarification
If you accept the potential formulation of Maxwell’s equations then Faraday’s law is a vector identity.

If you accept the conservation of magnetic flux then Faraday’s law can be derived using differential forms.

If you accept Coulomb’s law and relativity then Faraday’s law can be derived using tensors.
 
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funmi said:
How and why does a changing magnetic flux induce an emf? Why doesn't a static one also produce one?
How's this: with an emf or voltage, you can do work (run a motor, or heat a resistor, etc.), right? If you could do that with a static field, you would be getting something for nothing. You never get something for nothing, so you don't get emf from a static magnetic field.
 
gmax137 said:
How's this: with an emf or voltage, you can do work (run a motor, or heat a resistor, etc.), right? If you could do that with a static field, you would be getting something for nothing. You never get something for nothing, so you don't get emf from a static magnetic field.
Earlier he had a priori rejected any “if not then this would happen” explanations, but he appears to have changed his mind. So maybe this will satisfy him now.
 
I think the best answer is that that appears to be the way the laws of physics are. I'm not sure we know "why", although we can make other related observations and fit them all into a fairly simple and consistent set of laws that allow us to predict how nature works.

Watch this clip of one of the greatest intellects of the 20th century answer your question:
 
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DaveE said:
Watch this clip of one of the greatest intellects of the 20th century answer your question.

Came to find out about magnets, ended up learning why Aunt Minnie slipped on the ice. Joking aside, a pretty enlightening video.
 

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