Maxwell equations, curl problem

AI Thread Summary
The discussion revolves around the implications of Maxwell's equations, particularly Faraday's law and Ampere's law, in relation to the behavior of electric and magnetic fields. It addresses the confusion regarding the existence of these fields at the origin point, suggesting that while the fields are circular and may appear undefined at the center, they are not inherently zero or infinite. The conversation highlights that a field can be divergenceless without being undefined at a point, and that idealized models, like a wire with current, can complicate this understanding. Additionally, it emphasizes that the curl of a vector field does not imply a lack of origin or boundaries for the field itself. Overall, the relationship between electric and magnetic fields in electromagnetic waves is clarified, asserting their coexistence at the same point in space.
marcius
Messages
3
Reaction score
0
I have a question here about Maxwell's equations: according to faraday's law at some point in space changing magnetic field
with time creates the curl of electric field at that point and according
to Ampere's law with Maxwell's correction changing with time electric
field or electric current density creates the rotor of magnetic field.
So those created fields are circular, so it means that they should have no
beginning, so if electric field vector changing with time at some point
created circular magnetic field at that point, this magnetic field (that
was created) should be zero (or infinity, I'm not sure, but the field is
not defined) at origin point and exist only around it. The same is if
magnetic field induces electric. So if the created circular field is zero
at origin point and exists only aroud that point, it means that both
electric and magnetic field don't exist at the same point at the same
time. So how is with electrmagnetic waves when one field creates another
and they both exist at the same point in space, the graphs of functions (
Eosin(wt+kx) and Bosin(wt+kx) ) show that, because they exist at every
point ?
 
Last edited:
Physics news on Phys.org
Your question seems to say that the curl of a vector field is always zero or infinity. Please explain why.
 
Not like that. the curl is always defined and is neither zero nor infinity. But the field vector is zero, because field is circular, and the field vector is at origin of that circulation, so it should always be zero (or infinity) at its origin point. like there is no magnetic field (or its value its infinity) at the point in space, where the wire is.
 
Not that I really understand your question completely,but,first things first,I would like to point out that : "The Curl Of E is something,this doesn't signify that E has no beginning or end" If E were the Curl of something(E=Curl C,suppose),then you could say E doesn't have a beginning or end.
Baiscally, a field has to be divergenceless if it is without a source.
And Secondly,if a field is divergenceless,ie if it has no beginning or end,then this has no relation to the field being not defined at the origin.The magnetic field of a wire is a special case,a sort of idealization involving a line current.If you considered the wire to be of radius a,then the magnetic field wouldn't blow up at the axis.There are many easily imaginable current distributions such that the Magnetic field doesn't blow up at origin
 
Thread 'Motional EMF in Faraday disc, co-rotating magnet axial mean flux'
So here is the motional EMF formula. Now I understand the standard Faraday paradox that an axis symmetric field source (like a speaker motor ring magnet) has a magnetic field that is frame invariant under rotation around axis of symmetry. The field is static whether you rotate the magnet or not. So far so good. What puzzles me is this , there is a term average magnetic flux or "azimuthal mean" , this term describes the average magnetic field through the area swept by the rotating Faraday...
It may be shown from the equations of electromagnetism, by James Clerk Maxwell in the 1860’s, that the speed of light in the vacuum of free space is related to electric permittivity (ϵ) and magnetic permeability (μ) by the equation: c=1/√( μ ϵ ) . This value is a constant for the vacuum of free space and is independent of the motion of the observer. It was this fact, in part, that led Albert Einstein to Special Relativity.
Back
Top