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 'Griffith, Electrodynamics, 4th Edition, Example 4.8. (Second part)'

Thread 'Griffith, Electrodynamics, 4th Edition, Example 4.8. (Second part)'

I am reading the Griffith, Electrodynamics book, 4th edition, Example 4.8. I want to understand some issues more correctly. It's a little bit difficult to understand now. > Example 4.8. Suppose the entire region below the plane ##z=0## in Fig. 4.28 is filled with uniform linear dielectric material of susceptibility ##\chi_e##. Calculate the force on a point charge ##q## situated a distance ##d## above the origin. In the page 196, in the first paragraph, the author argues as follows ...
View full post »
Thread 'Inducing EMF Through a Coil: Understanding Flux'

Thread 'Inducing EMF Through a Coil: Understanding Flux'

Thank you for reading my post. I can understand why a change in magnetic flux through a conducting surface would induce an emf, but how does this work when inducing an emf through a coil? How does the flux through the empty space between the wires have an effect on the electrons in the wire itself? In the image below is a coil with a magnetic field going through the space between the wires but not necessarily through the wires themselves. Thank you.
View full post »

Similar threads

I Is the Poynting Vector Field the Only Factor in Energy Flow in Circuits?
Replies
16
Views
3K
B Electric Field Created by 2 Infinite Plates
Replies
1
Views
1K
How do I generate a magnetic vector field using equations?
Replies
17
Views
2K
I Electric field vector takes into account the field's radial direction?
Replies
3
Views
1K
I E field in a wire
Replies
3
Views
254
An Interesting Question on Faraday's Law of Electromagnetic Induction
Replies
11
Views
3K
I Help with electromagnetics: the Poynting Vector and Ampere contradiction
Replies
14
Views
3K
Induced Electrical Field (Maxwell-Faraday's Law)
Replies
4
Views
2K
B Magnetic field and generator power output
Replies
5
Views
2K
A Voltage and current waves in a transmission line
Replies
4
Views
3K

Hot Threads

Recent Insights

Back
Top