Electric Field and Magnetic Conversion

AI Thread Summary
The discussion centers on the relationship between electric and magnetic fields in the context of the Poynting vector and average power. It clarifies that the proposed equation B = E /(2μ0c) is incorrect. The correct relationship for a wave in free space is B = (1/c) E, where E and B are perpendicular to each other and the direction of propagation. The average power expression is derived from the Poynting vector, which is defined as S = (1/μ0) E × B. The conversation concludes with a confirmation of the correct relationships between these electromagnetic quantities.
onelastdance
Messages
6
Reaction score
0
In the solutions of a particular problem, it was stated that:

<P> = 1/2 |S| = 1/(2μ0) * E^2 / c

Where <P> is the average power, S is the Poynting vector.

From the above equation does that mean: B = E /(2μ0c) ?

I was just wondering how you can show the above relation between Magnetic and Electric field.
 
Last edited:
Physics news on Phys.org
No it doesn't. The Poynting vector is \mathbf S=\frac{1}{\mu_0} \mathbf E \times \mathbf B
and, for a wave propagating in free space, B and E are normal to each other (and to the direction of propagation) and have magnitude B = \frac{1}{c} E. Look it up. When you take a time average to get power, it devolves to your first expression.
 
Last edited:
Oh ok, thanks.
 
Last edited:
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...
Back
Top