Why does a change of magnetic flux induce an EMF?

Click For Summary
SUMMARY

A changing magnetic flux induces an electromotive force (emf) due to Faraday's law of electromagnetic induction, which states that a time-varying magnetic field creates an electric field. Static magnetic fields do not produce emf because they do not perform work on charged particles, aligning with the principle that energy cannot be created from nothing. The discussion emphasizes the importance of accepted physical laws, such as Maxwell's equations and the conservation of magnetic flux, in understanding these phenomena. The intuitive explanation provided highlights the relationship between motion, magnetic fields, and induced emf.

PREREQUISITES
  • Understanding of Faraday's law of electromagnetic induction
  • Familiarity with Maxwell's equations
  • Basic concepts of electric and magnetic fields
  • Knowledge of the principle of conservation of energy
NEXT STEPS
  • Study Maxwell's equations in detail
  • Explore the practical applications of Faraday's law in electrical engineering
  • Learn about the relationship between electric fields and magnetic fields
  • Investigate the implications of the conservation of energy in electromagnetic systems
USEFUL FOR

High school students, physics enthusiasts, and educators seeking to understand the principles of electromagnetism and their applications in real-world scenarios.

funmi
Messages
10
Reaction score
1
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.
 
Last edited:
Physics news on Phys.org
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.
 
  • Like
Likes   Reactions: DaveE
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.
 
  • Like
Likes   Reactions: etotheipi and berkeman
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:
 
  • Like
Likes   Reactions: Dale
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.
 

Similar threads

  • · Replies 5 ·
Replies
5
Views
664
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 27 ·
Replies
27
Views
3K
  • · Replies 42 ·
2
Replies
42
Views
3K
  • · Replies 194 ·
7
Replies
194
Views
22K
  • · Replies 10 ·
Replies
10
Views
4K
  • · Replies 4 ·
Replies
4
Views
3K
  • · Replies 9 ·
Replies
9
Views
2K
  • · Replies 9 ·
Replies
9
Views
4K
  • · Replies 3 ·
Replies
3
Views
17K