All Questions
Tagged with electromagnetic-radiation electric-fields
233
questions
7
votes
7
answers
4k
views
Is it impossible to construct a Faraday cage that can block a *static* electric field?
I think the answer is yes. My reasoning is this: Imagine for argument's sake, we could have a charged negative source that has its field blocked by a Faraday cage. We can transport a positive charge ...
- 6,102
1
vote
0
answers
16
views
Why is the intensity of a beam of light the squared magnitude of the phasor and not just the squared magnitude of the real part?
I'm learning about phasors and light intensity and there are two conflicting things I've been told that I can't reconcile.
Firstly I've been told that a phasor $e^{-ikz+i\phi}$ is a mathematical way ...
- 531
0
votes
2
answers
102
views
Why In an electromagnetic wave both electric and magnetic waves are in sync and perpendeculare? if one makes the other shouldnt there be a delay? [closed]
Why are electric and magnetic waves in phase if one induces the other? Shouldn't there be a delay, similar to how potential energy converts to kinetic energy and vice versa? Additionally, why are ...
- 21
1
vote
1
answer
54
views
Is $\vec E$ more effective than $\vec B$ and why?
While reading about the Poynting vector in Optics (5 ed) by Eugene Hecht, I found the following line in page 42, from chapter 3.
Since, as we have learned, $\vec E$ is considerably more effective at ...
- 13
1
vote
1
answer
51
views
Why isn't the original EM wave in a beam of light in a medium not still detectable from a distance as if it were moving at the speed of light?
I'm learning optics and I've been told that the reason light slows down in glass is because the Electromagnetic field of a beam of light interacts with and accelerates charged electrons in glass ...
- 531
0
votes
2
answers
53
views
Are all recursive interactions between electric and magnetic fields always orthogonal to each other?
ecursively, this implies that changes in the electric field generate the magnetic field, and vice versa, akin to the plane wave solution resulting from specific boundary conditions intentionally ...
- 21
0
votes
2
answers
78
views
The electric field due to a moving charge is in radial direction as well. Why?
According to special relativity the information can transmit only at the speed of light. However,the electric field at a point due to a charge moving at constant velocity changes its direction the ...
- 353
-2
votes
1
answer
55
views
Can light propagate in the absence of electric and magnetic fields?
It has been established that light or other forms of electromagnetic radiation needs electric and magnetic fields in order to propagate. What would happen if it were possible to shield an area from ...
1
vote
1
answer
125
views
Can an electromagnetic wave be polarised in the direction it propagates?
Can the electric field vector of an EM wave oscillate in the propagation direction?
In text books the polarisation is always orthogonal to the propagation direction.
I'm wondering specifically ...
- 21
0
votes
1
answer
61
views
Solving Maxwell Equations when a charge is put inside a generic conductor
A net point-charge density $\rho_0$ is impressed without speed (no impressed current density) at position r0 at time $t_0$. Relaxation analysis tells us the charge density will decrease exponentially ...
- 1,319
0
votes
2
answers
124
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Does gravity affects electromagnetic waves? Or electromagnetism affects gravity?
I'm confused about the relationship of electromagnetism and gravity, or are they even related?
It has been said the electromagnetic field produces a gravitational field, and so, there is no gravity if ...
0
votes
1
answer
62
views
Understanding sources (charge and current densities) in Jefimenko Equations
Let's consider the two Jefimenko Equations:
$$E(r,t) = \frac{1}{4πϵ_0}∭_V[\frac{e_{r-r'}}{|r-r'|^2} ρ(r',t_r' )+ \frac{1}{c} \frac{e_{r-r'}}{|r-r'|} \frac{∂ρ(r',t_r')}{∂t} - \frac{1}{c^2} \frac{1}{|...
- 1,319
4
votes
3
answers
164
views
Origination of electromagnetic wave energy
Please correct me if I am wrong in my statements
While it is said that electromagnetic waves are formed by the oscillation (acceleration) of charges which forms 'kinks' in their electric field which ...
- 87
0
votes
1
answer
92
views
Energy of Monochromatic Beam of Light
A monochromatic beam of light has energy
$$ E_{\text{beam}} = N \hbar \omega, $$
$ N $ being the number of photons in the beam and $ \omega $ their frequency.
Another way to evaluate this energy is ...
0
votes
0
answers
44
views
Why is the expression for the electric field vector on a point in space originating from a moving point charge this way? [duplicate]
I was studying light as electromagnetic radiation in Feynmann's lectures book (Vol. 1, Ch. 28) and, in explaning how radiation works, he gives the following expression for the electric field at a ...
- 21