Questions tagged [electromagnetism]

The classical theory of electric and magnetic fields, both in the static and dynamic case. Also covers general questions about magnets, electric attraction/repulsion etc. Distinct from electrical-engineering.

Filter by
Sorted by
Tagged with
-2
votes
2answers
42 views

Is voltage basically the measure of the strength (or density) of an electromagnetic field? And does an increase in voltage increase the amperage?

I have been in the process of fully understanding what is generally accepted as truth by the scientific community regarding voltage, watts, and amperage. Most engineers seem to say to simply use the ...
-2
votes
3answers
280 views

Self Induction and Inductance [closed]

A coil with zero resistance has its ends labeled a and b. The potential at a is higher than at b. Which of the following could be consistent with this situation? Mark all that apply a. The current ...
-2
votes
1answer
581 views

Working of betatron [closed]

Can anyone please explain me the working principle of betatron and is it better than cyclotron or not in terms of accelerating particles at greater speed and energy consumption by the instrument used ...
-2
votes
2answers
77 views

Can I turn a thin steel rod into an electromagnet and have it collect statically charged dust?

I frequently move dust/salt-like material from one small plastic container to another. I do this with a steel rod about 3x the thickness of a paper clip that has a flattened end. Sometimes the ...
-2
votes
1answer
234 views

Work done by 2 Magnets when they attract each other

]1 Assuming that whatever is written (in the picture) is true,then how is work done when 2 magnets attract each other in space. Even they should not do any work but by observation, they do come close
-2
votes
1answer
115 views

Inhomogeneous wave equation by fourier in analysis

$$\nabla^2\psi_\omega+\frac{\omega^2}{c^2}\psi_\omega=-g\omega,\tag{14-16}$$ which is similar to Poisson's equation. We may synthesize the solution of Eq. (14-16) by the superposition of unit ...
-2
votes
1answer
38 views

Induced Current in Uniform B-Field [closed]

In each of the following cases, mark the directions of the induced current $I$ in the conductor and the magnetic force $F$ acting on the conductor when the circuit moves in the direction as shown. ...
-2
votes
1answer
211 views

How do I convert Nm/Kg in MGOe? [closed]

i have to buy a few magnets of a certain attraction intensity, i would like to know how to convert Nm / Kg in MGOe. What is the formula? Can you please make an example for 100 Nm/Kg?
-2
votes
1answer
65 views

Is there a difference in the emitted EM radiation from electrons with same kinetic energy coming in rest in an hydrogen atom and in a magnetic field?

I had a question about https://physics.stackexchange.com/questions/320426/what-prevents-us-to-build-a-model-where-in-the-atom-the-positive-and-negative-el?noredirect=1#comment720010_320426. The ...
-2
votes
1answer
471 views

How can electric field and magnetic fields have x and y components in electromagnetic wave?

Suppose an electromagnetic wave is travelling in z direction with electric field in x direction and magnetic field in y direction. Then how can electric field and magnetic field vectors have both x ...
-2
votes
2answers
701 views

A magnets north pole and south pole

Why does the N pole of a magnet do not attract with the same pole but the N pole of a magnet attracts with S pole?
-2
votes
1answer
726 views

Lorentz invariance of wave equation

Recently, I was wondering if the homogeneous wave equation is Lorentz invariant. It can be easily proved that the operator $\Box$ is invariant under Lorentz transformations, and so I concluded that, ...
-2
votes
2answers
1k views

Vector potential from magnetic field

If a uniform magnetic field ${\bf{B}}=B_{z}{\bf{\hat{z}}}$ exists in a hollow cylinder (with the top and bottom open) with a radius $R$ and axis pointing in the $z$-direction, then the vector ...
-2
votes
1answer
245 views

Mechanism by which a capacitor is charged, using surface charges

I want to gain a deeper understanding as to how a capacitor actually gets charged. Consider a situation in which an uncharged parallel plate capacitor is connected to a battery using two wires. I ...
-2
votes
3answers
120 views

does a one bar electric fire exhibit electron decay?

I know you guys have spent a lot of time proving that electrons don't decay, but could somebody explain what comes out of my one bar electric fire when I switch it on - particularly if its not ...
-2
votes
1answer
103 views

How to find the magnitude of electric and magnetic fields in an arbitary inertial frame?

In the context of special relativity, and using proper Lorentz transformations: If the electromagnetic fields have an uniform value [= constant in space and time] in an inertial frame, how will the ...
-2
votes
1answer
102 views

Weight of magnetic objects and polarization [closed]

I am an Iranian engineer and have a question which no one has answered me yet. In weighing a strong magnet, there is a difference between the weights from different polarization directions, why is ...
-2
votes
3answers
121 views

Crazy? Generate unusable electricity [closed]

I know that sounds crazy, but today I am wondering if there is a way to generate a current that is unusable by almost all electric/electronic devices? The idea would be to generate that current and ...
-2
votes
1answer
65 views

How to convert EM fields to EM waves?

How a body producing electricity and magnetic fields become a body radiating electromagnetic waves?
-2
votes
1answer
116 views

Does magnetism only work on ferrous objects? [closed]

Ordinary magnets can attract only ferrous objects (correct if i am wrong), but celestial bodies attract almost anything (including light). Are these different types of magnetism?
-2
votes
1answer
123 views

How to calculate transmission? [closed]

How to calculate transmission of photonic fibers? I dont see chapter about photonic fibers in the Agrawal book.
-2
votes
1answer
185 views

Maxwell equations [closed]

$$\oint B.dl = \mu_0\left(I+\epsilon_0\frac{\partial\Phi_E}{\partial t}\right)$$ Please explain the applications , and implications of the modified Ampere's circuital law with Maxwell's addition. ...
-2
votes
1answer
194 views

Current and emf in a transformer

In the book Fundamentals of Physics by Halliday, Resnick and Walker(Extended)(6th edition), in a an ideal transformer it is written that the current induced in the secondary coil induces an opposing ...
-2
votes
1answer
1k views

The acceleration of a particle in uniform electro-magnetic field [closed]

A particle of charge $q$ and mass $m_0$ is subject to the action of a uniform electro-magnetic field $\vec{E}=(0,E,0), \vec{B}=(0,0,B)$ and at $t = 0$ moves with velocity $\vec{v}=(v_1,v_2,v_3)$. ...
-2
votes
0answers
73 views

How exchanging virtual particles works as a fundamental force (other than gravity)?

Force is rate of change of momentum. But is my following description of how exchanging virtual particles can mediate a fundamental force (other than gravity) correct? If there are $2$ subatomic ...
-2
votes
1answer
40 views

Acceleration through potential difference [closed]

Fe^1+ ions are accelerated through a potential difference of V volts. What does this statement even mean???Please explain it to me. And please give me a general formula to work out the velocity ...
-2
votes
1answer
66 views
-2
votes
1answer
73 views

Building the Lagrangian of electromagnetism from the Lorentz invariant?

The definition of the relativistic Action is $$ S=\int_a^b ds $$ The Lorentz invariant of electromagnetism is $$ s^2=\frac{1}{c^2}||\mathbf{E}||^2-||\mathbf{B}||^2-2i\frac{1}{c}(\mathbf{B}\cdot \...
-2
votes
2answers
299 views

Dimensions of mass in terms of Length and Time

From Maxwell's Treaties on Electricity and Magnetism: For acceleration due to attraction of a mass m at a distance r is by the Newtonian Law m/(r^2). Suppose this attraction to act fro a very small ...
-2
votes
1answer
67 views

Understanding equation 11.11 in Griffiths “introduction to electrodynamics” [closed]

I am reviewing my electrodynamics and stumbled upon an approximation in Griffiths "introduction to electrodynamics" which I still don't understand after ponding on it. My question is: How does he ...
-2
votes
6answers
93 views

Electric charges cannot move

I have already posted this in the past but it was closed because it was too vague, I wasn't able to formulate a good question and so no one really understood what I meant. Since then I still haven't ...
-2
votes
1answer
146 views

How to tell whether to add magnetic field lines or subtract?

Hi there, When you draw the magnetic field lines around these two current-carrying wires, after solving the magnetic field strength around each one (X and Y), how do you know whether to add them or ...
-2
votes
1answer
50 views

How can an electromagnetic wave propagate on itself even if there is no source that has created it? [duplicate]

How can an electromagnetic wave propagate on itself even if there is no source that has created it?
-2
votes
3answers
191 views

why electrostatic force is called force

My title looks bit silly but I will explain my question . Why have the nucleus of atom and why have electrons circulating outside of nucleus force the cause electrons to stay in proximity to ...
-2
votes
1answer
224 views

Linear Superposition Principle vs Energy Conservation during propagation of EM waves

Think about focusing an EM beam, and having a divergent beam past the focus. Let r be the distance from the focus to a measurement point. The Linear Superposition Principle implies that the electric ...
-2
votes
1answer
112 views

Consider three infinitely long thin wires [closed]

Each carrying current I in the same direction , are in $x$-$y$ plane. The central wire is along the $y$ axis, while the other along $x=+d$ and $-d$ Find the locus of points for which magnetic field ...
-2
votes
1answer
220 views

Finding the current in a light bulb [closed]

I am doing this practice problem where it asks me to find the current through the light bulb at two different temperatures. The problem I am having is that I cannot find out how to do the problem with ...
-2
votes
1answer
456 views

Curl of magnetic field

Why is the curl of a magnetic field due to a current carrying wire zero everywhere, and infinite in the wire itself?
-2
votes
1answer
103 views

What's the third equation that allows solving the closest approach of two electrons?

Lately, I have been thinking about the following situation: in one-dimensional space, if we have two electrons, and one of them is stationary while the other approaches with some velocity, what would ...
-2
votes
1answer
933 views

How does a changing magnetic field induce an emf?

I don't understand how a changing magnetic field or how changing magnetic flux induces an emf. Im trying to find out how a electric geneartor works. Does the magnet pull the electrons toward the south,...
-2
votes
2answers
76 views

The exact nature of electromagnetic charge [duplicate]

It is an assumed that positive and negative electromagnetic charges,"attract" each other. But what IS charge?
-2
votes
1answer
95 views

Magnetic potential and magnetic field assumptions

I've seen many proofs where you want to find the magnetic field inside and outside a solenoid for example. The author said using symmetry magnetic potential is a function of some variables and discard ...
-2
votes
2answers
827 views

Electromagnetism and electrostatic forces. How are they related and different?

So I am new to the stuff of electromagnetism, and frequently when talking about electromagnetism, you hear of electrostatic forces as well. What are the differences between the two and how are they ...
-2
votes
1answer
77 views

Does the Aharonov-Bohm effect change the phase of all wavefunctions in the Universe?

In the double slit experiment with electrons, the interferential pattern on the screen is shifted in the presence of a long thin coil (through which of a current flows, Naturally) between the double ...
-2
votes
2answers
97 views

Is it possible to make a scooter that is propelled by perpetual magnets (without converting it to electricity)? [duplicate]

I am, along with two of my classmates, are planning to make a prototype of a scooter (as in slower, smaller version of a motorcycle) that is propelled by an infinitely turning magnet wheel. Not as a ...
-2
votes
1answer
53 views

Suppose you put free charge on a conductor. After how long will it reach the surface? [closed]

Iam unable to solve this question. (https://i.stack.imgur.com/EoiAx.jpg)
-2
votes
2answers
72 views

I wish to inquire whether there is any kind of magnet that can be used to push away a metal other than attract!

I wish to inquire whether there is any kind of magnet that can be used to push away a metal other than attract it.. or what can be done to create eddy currents that can do that!
-2
votes
1answer
40 views

current flow tangent to the wire

In a thread flowing a current. How is it possible that the current is always tangent to the wire, regardless how the driver is "bent"?
-2
votes
1answer
41 views

What type of energy comes off powerlines that can be photographed or seen

Like in my photo of powerlines ..what's one to call that??
-2
votes
1answer
143 views

How can current remain same when potential difference decreases?

According to Ohm's law, $$\text{potential difference} = \text{resistance}\times\text{current}$$ Also, current remains the same everywhere. Now when current passes through a bulb, the electric ...