All Questions

Filter by
Sorted by
Tagged with
0
votes
2answers
38 views

What really is an electric/magnetic field?

Have you ever wondered how we can see this field or how it's formed its shape in space? I know we can feel that there's one by its effect which is the force. But what does it look like? We all know ...
0
votes
2answers
44 views

How can a spring contract when magnetic field cannot do work?

When a spring is kept in a magnetic field and current is passed through it, its edges act as parallel conductors and due to the action of Lorentz force, they pull themselves together. A spring ...
0
votes
2answers
34 views

Visualization of electromagnetic waves with potentials?

I wonder if there is out there any visualization of the propagation of electromagnetic waves, not only with the electric and magnetic fields components but an actual visualization of the underlying ...
-3
votes
1answer
56 views

Regarding the Lorentz force:

I know that the Lorentz Force law states that: $\vec{F} = q\vec{E}+q\vec{v} \times \vec{B}$ And then for the magnitude of the force, where $q_2$ is the moving charge: $E = F/q_2$, and therefore $E =...
1
vote
0answers
31 views

Electromagnetism:field and waves [closed]

What does the area under the graph of anEM wave represent?,is it the magnitude of the area of the electomagnetic field?
0
votes
0answers
26 views

How to calculate the velocity and radius of curvature of a charged particle in a perpendicular magnetic and parallel electric field?

If I have a charged particle come from a point velocity V1 where there is a uniform electric field parallel to the motion of the particle which accelerates it and a magnetic field perpendicular to ...
2
votes
2answers
129 views

Derivation of Ampere's Law from Biot-Savart

Our aim is to derive $\nabla\times \mathbf B=\mu_0(\mathbf J+\epsilon_0\frac{\partial E}{\partial t})$. To begin with, let $ \mathbf A=\frac{\mu_0}{4\pi}\int_{\mathbb R^3}\frac{\mathbf J(\mathbf r')}{...
0
votes
1answer
41 views

How electric field and magnetic field propagate through vacuum where there's no charge present? [duplicate]

As we know light travels as an electromagnetic wave...but electric fields and magnetic fields are interactions between charges...they are the forces acting on stationary and moving charges ...
0
votes
1answer
29 views

Electric field due to changing uniform magnetic field

I think this could be a misunderstanding on my part , still I want to clarify this.Suppose in a region of boundless expanse, there is a uniform magnetic field which changes at a rate $\frac{d\phi}{dt}$...
1
vote
1answer
73 views

EM-Wave: Calculate magnetic field $H$ from electric field $E$

In an exercise I am supposed to calculate the magnetic field from the electric field for a plane, harmonic wave in vacuum. $$\vec{E} = - E_0 \cdot \sin(\omega t - k z) \cdot \vec{e_y}$$ Using the law ...
0
votes
2answers
33 views

What do you see when you are inside a transparent conducting material?

Lets say that there exists a transparent conducting material. Lets carve a cavity in the meat of the conductor big enough for a person to stay in. There exists an external electric field. But, We ...
2
votes
4answers
121 views

Electromagnetic waves according to Maxwell

If a variable Electric field creates a variable magnetic field and VICE VERSA (according to Maxwell's equations), then why don't we enter a loop where E vector and B vector keep creating one another ...
0
votes
0answers
16 views

Guided propagation in transmission lines

Can you help me on understanding why we may say this transmission line the propagation is guided and there is not any radiation? It is a 2-conductors transmission line, in which the conductors are ...
1
vote
0answers
41 views

Is the flow of charges in inductor though electric field zero?

How electric field inside the wire of an inductor is zero (i.e. material of which loop is made — note material is assumed to be a superconductor), then how electrons flow in an inductor if electric ...
4
votes
2answers
85 views

Complex vectors: Electric and Magnetic Fields

I have a doubt about the physical meaning of the complex representation of electric and magnetic fields. Let's consider an electromagnetic wave, in which both electric and magnetic fields propagate ...
0
votes
0answers
20 views

Velocity Selector Question with Unknown Voltage

In a diagram, electrons are emitted from a hot coil with initial velocity 0 at plate A and then pass through a uniform field between two plates (A and B) where $V=1.00\times10^4$ volts. After, they ...
0
votes
1answer
58 views

The electric and magnetic field, reaching to infinity

I have difficulty’s to accept that the electric and magnetic field components of photons as well as of electrons and the other subatomic particles are extended to infinity. For practical use that does ...
0
votes
1answer
79 views

What happens with the divergence of maxwell stress tensor when EM fields in vacuum?

The conservation momentum can be derived from the total electromagnetic force on the charges in volume $V$ and is written in this way: $$ \frac{d\vec{p}_{mech}}{dt} + \frac{d}{dt} \int_V (\vec{E}\...
0
votes
1answer
26 views

Physical Relation in Maxwells Equations of quantity between as well as fundamental forces

Recently learnt about Maxwells Equations, am wondering what is the physical relation between electric field E and magnetic field B. It would help if the physical meanings are related to the ...
0
votes
4answers
95 views

Can every mass obey the Newton's 3rd law?

As in, if we were able to produce a very huge amount of force on a very small body, would it push back with the same force? Given it doesn't break or disintegrate. Like if we electromagnetically put ...
0
votes
0answers
18 views

The issues when thinking about the magnetic flux law as being universal in modeling

$$ \varepsilon = -\frac{\partial \Phi}{\partial t} =-\frac{\partial (BA)}{\partial t} $$ Any instance of considering the emf induced in a system, I usually think of the flux law first, I intensely ...
0
votes
1answer
55 views

How cavity magnetron works?

I've found an explanation on explainthatstuff.com. There are these electrons from the cathode that are going around in a circle (because of the magnetic field), passing next to the cavities. Then it ...
1
vote
1answer
27 views

Relationship between the: Power supply's electric force for current flow, and Lorentz force equation for electric force?

$$ F = qE + qv \times B$$ For the Lorentz force relevant to a current carrying wire, that is caused by the motion of a wire w.r.t to an exterior magnetic field $B$, the second term($qv \times B$) on ...
3
votes
1answer
91 views

Does a homogeneous oscillating electric field produce a magnetic field?

I am working on a homework problem that says an electron in a continuous laser field can be modeled as experiencing a homogeneous oscillating electric field $\vec{E}(\vec{r},t)=\cos \omega t \ \hat {z}...
0
votes
0answers
31 views

Ion separation is effected by static or dynamic electric or magnetic fields?

My textbook says the following: The basic principle of mass spectrometry (MS) is to generate ions from either inorganic or organic compounds by any suitable method, to separate these ions by their ...
0
votes
0answers
24 views

Regarding induced magnetic field due to changing electric field

I am trying to solve this question: My approach was to first notice that the electric field is decreasing, therefore the change in electric field is to the left. If I point my thumb in the direction ...
0
votes
1answer
63 views

Lorentz transformations: Distance vs “retarded distance”

Suppose I have a charge situated at rest in one inertial coordinate system. The field of that drops inversely with the square of the distance. If I perform a Lorentz boost where $$v^2« c^2$$ (not ...
4
votes
2answers
36 views

Derivation of $B$ field and $E$ field

For an infinite plate of charge, the E field is (density of charge per area) divided by (2*vacuum permittivity). In deriving it, we used Gauss' Law and say that the flux through the two ends of the ...
0
votes
1answer
40 views

Is the electric field from light independent from the light magnetic field?

I was reading about antennas and I found an statement somewhat like this "loop antennas are more efficient compared to other antennas when close to the human body since the human body interacts more ...
0
votes
1answer
82 views

An $E$ field with no $B$ field in a region?

Assume there exists a time-varying current source ${\bf J}({\bf r},t)$ in otherwise vacuum and a region $R$ that does not intersect the region of support for ${\bf J}({\bf r},t)$ (That is ${\bf J}({\...
2
votes
1answer
58 views

If electricity creates a magnetic field, could a (strong) magnetic field stop electricity? [closed]

Surely this would make the two magnetic fields interact and if movement was made impossible, the stronger magnetic field would block the weaker electromagnetic filed. Am I right (presuming that the ...
1
vote
1answer
52 views

Induced Electric Fields and Faraday's Law

I'm an undergraduate student and we just covered Faraday's law. However, I am still confused conceptually about a few things: Faraday's law states that $\oint_{\partial\Sigma} \vec{E} \cdot \vec{dl} =...
0
votes
1answer
100 views

Helical motion of a charge in magnetic and electric field

Suppose there is a positive charge undergoing circular motion in the x-y plane because of a magnetic field acting in the negative z direction. If a uniform electric field is switched on in the same ...
0
votes
0answers
57 views

Counter Torque in Electric Generator

I am going to use some sort of “dynamo” or electric generator component to generate electricity from the flowing drilling fluid. However, the effect of the magnet rotating within an electrical coil ...
0
votes
1answer
55 views

What electric and magnetic field lines look like in some examples?

I have seen this but couldn't understand so I wrote my own question. We all have learnt in school that electric field lines never intersect. Same is the case for magnetic field lines. But I have a ...
4
votes
4answers
125 views

Does Electromagnetic wave propagation really use $E$ to create $B$

I was studying how electromagnetic waves (EM waves) were generated and propagated. I was shown a dipole antenna with an AC source sloshing charges back and forth. To my understanding, when the ...
1
vote
0answers
41 views

why doesn't EM waves get weaker as we travel further away from the source [duplicate]

I know that as we get further away from the charge or from the magnetic field source both magnetic field and electric field decreases ,so why don't electromagnetic waves get weaker as the travel ...
3
votes
1answer
103 views

Why do we assume simply connected domains and continuously differentiable fields in electromagnetism theory?

In many textbooks, including Griffiths', they erroneously claim that a field is irrotational if and only if it is conservative (there exists a scalar potential). This is true only if the domain of ...
-1
votes
2answers
143 views

Why can't a particle that carries magnetic charge exist? [duplicate]

Electron is the source of electric field and changing electric field produce magnetic force, what about particle that can do vice versa? My concern is how come universe favors particles that carry ...
3
votes
1answer
115 views

Is there is any way to prove the Faraday's law of induction?

I want to know if there is any way to prove the Faraday's law or is it just an experimental observed phenomena? More specifically, is there any reason why the proportionality constant is 1? How did ...
2
votes
0answers
124 views

Proof that true passive linear memristors don't exist

This is a sequel to the following (now irrelevent) question: My attempt to implement linear memristor Assume the "conceptual symmetry" of the fundamental passive circuit elements holds: Then let's ...
3
votes
2answers
462 views

Are Kirchhoff's Laws violated in case of varying magnetic field?

I was watching a video of Walter Lewin (8.02x-Lecture 16 to be precise), where he demonstrates an experiment which violates the Kirchhoff's Law. The way I interpret Kirchhoff's laws is by ...
0
votes
3answers
48 views

What actual difference does it make whether electric or magnetic field lines are open or closed?

If both electric and magnetic fields attenuate with distance by the inverse square law, what difference does it make that the latter's field lines are 'closed'? And if a magnetically-induced electric ...
1
vote
0answers
73 views

How does a time varying magnetic field induce an electric field?

I've been trying really hard to understand this phenomena. Just exactly what happens in the region of space swarmed by this changing magnetic field that creates non electrostatic electric fields, ...
2
votes
1answer
83 views

Should loop choice affect induced electric field?

Let's say we have a time varying magnetic field, but that it is uniform over a region, for instance $B(x,y)=(t+2)\hat{z}$ for $x,y,z\in[-5,5]$. Since we have a changing magnetic field, there will be ...
1
vote
1answer
45 views

Particle accelerator adapted to transport humans

Would it be possible to create a human transport system that uses the same principles as a particle accelerator? So if you had a vacuum tube that could fit a 2 m diameter metallic sphere/pod that ...
0
votes
1answer
54 views

Do Electromagnetic waves exert equal force on positive and negative charges?

Waves in the Electromagnetic fields propagate with the speed of light and have perpendicular E- and B-components. These components should exert a Lorentz force on a charged particle that exists in the ...
1
vote
2answers
608 views

How can I detect an electric field?

I can easily detect the presence of magnetic field over a surface by using compass or by placing some iron filings. But how could we similarly detect electric field over a place?
1
vote
1answer
41 views

All magnetic effects, simply provided by a contracted electric field?

Is the contracted electric field of constantly moving charge is what we call a magnetic field? Does the charge, that moves in a straight line has a north and south poles? Contracted electric field has ...
0
votes
1answer
48 views

Direction of magnetic field lines around a conducting wire

By way of the first uploaded picture I was taught that magnetic field-lines around a long conducting wire with a current are shaped like concentric circles around the wire. However, a few pages ...