# 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.

11,068 questions
Filter by
Sorted by
Tagged with
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 ...
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 ...
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 ...
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 ...
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
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 ...
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. ...
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?
65 views

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 ...
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?
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, ...
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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
65 views

### How to convert EM fields to EM waves?

How a body producing electricity and magnetic fields become a body radiating electromagnetic waves?
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?
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.
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. ...
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 ...
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 $\vec{v}=(v_1,v_2,v_3)$. ...
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 ...
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 ...