# Why is EMF generated by changing magnetic flux? please help

I am fixed to find out the reason what makes the charges get separated in conductor causing an emf leading to induced current. A very good reason exists for motional emf. It can be explained with the help of F=qvBsinΘ.

## Answers and Replies

Simon Bridge
Homework Helper
Welcome to PF,
... what have you discovered so far?

berkeman
Thank you Simon---- nothing found so far----- I got a clue from Physics Forum that as changing magnetic fields produce changing electric fields no matter there is any conductor nearby or not---- So if a conductor is placed in a variable magnetic field, the electric field produced by this changing magnetic field will force separation of charges in the conductor causing induced emf----- This idea seems convincing but I need more authentic comments of more experienced fellows of PF------
By the way I am impressed and inwardly very happy that I have found a place where I ll be able to ask and share my queries. Thank you once again.

Jeff Rosenbury
Thank you Simon---- nothing found so far----- I got a clue from Physics Forum that as changing magnetic fields produce changing electric fields no matter there is any conductor nearby or not---- So if a conductor is placed in a variable magnetic field, the electric field produced by this changing magnetic field will force separation of charges in the conductor causing induced emf----- This idea seems convincing but I need more authentic comments of more experienced fellows of PF------
By the way I am impressed and inwardly very happy that I have found a place where I ll be able to ask and share my queries. Thank you once again.
That's a fair description, but whomever asked will likely want numbers. You might research Maxwell's equations.

Still, these equations describe what is happening, not why. These equations were found through observation. (Science is all about observation.) They are axiomatic and not usually explained.

I've never heard or read of an explanation about why the electromagnetic field inter-relates the way it does. It might have something to do with quantum probabilities. Perhaps someone on the quantum forum has a clue?

But remember science is about what is happening, measured through observation. We leave why to the philosophers and religious leaders.

Ahhh.. listen to the master - if you wish jump to 4:57 - YouTube -

Edit - the Link is to Prof Lewin lecture on this issue at MIT courseware... not a trivial / stupid you tube video. If you are asking this topic you should watch this lecture.

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I opened a thread on the quantum forum and got two reasons.

Both are for advanced students. One is from a quantum perspective and one is more relativistic.

Thanks to DEvens and jtbell.

I am always awed at how well the standard model fits together.

meBigGuy
Gold Member
Actually, it is more appropriate to ask on the relativity forum.

This isn't the answer, but gets you started.

Also, Feynman explains a lot in this lecture: http://www.feynmanlectures.caltech.edu/II_13.html Section 13.6

I had a thread discussing this a while back:

Electric and magnetic fields are different views of electromagnetic fields. Maxwell's equations don't deal with the relativistic issues because of their initial conditions

cnh1995
Thank you Windadct, Jeff Rosenburry and meBigGuy for putting me on a track---- I am studying these articles and will listen to Professor Lewin--- my all time favorite teacher--- I ll come back with something appropriate to share on this forum--- Regards

That's a fair description, but whomever asked will likely want numbers. You might research Maxwell's equations.

Still, these equations describe what is happening, not why. These equations were found through observation. (Science is all about observation.) They are axiomatic and not usually explained.

I've never heard or read of an explanation about why the electromagnetic field inter-relates the way it does. It might have something to do with quantum probabilities. Perhaps someone on the quantum forum has a clue?

But remember science is about what is happening, measured through observation. We leave why to the philosophers and religious leaders.
Dear Jeff --- agreed-- in most cases have no answers or explanations of natural phenomena and take them as axiomatic--- but luckily there are still a lot left where reasonable justifications can be given---- As physics teachers we are supposed to give justifications and explanations to our students for such happenings----

Simon Bridge
Homework Helper
Side issues...
I need more authentic comments of more experienced fellows of PF
Scientists rely on Science, not authority... the most experienced of people can still be wrong.

As physics teachers we are supposed to give justifications and explanations to our students for such happenings
Surely physics teachers should give lessons about physics.
Nature may need explaining, but never justification... we leave the "why" stuff to philosophers or we do our students an injustice. A scientific explaination is a description of how different phenomena may be related.
You may want to look at some "philosophy of science" courses.

Jeff Rosenbury
Nature may need explaining, but never justification... we leave the "why" stuff to philosophers or we do our students an injustice. A scientific explaination [sic] is a description of how different phenomena may be related.

From your mouth to God's ears -- as it were.