Tagged Questions

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.

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Basic EM: Infinite energy of magnetic field?

I thought I was done with EM, but then I encountered a strange question: A ring of test mass (m) and test charge (q) with radius R is sitting still in space filled with a uniform B-field in the ...
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Induced motional EMF where the wire is stationary and the field source is moving?

If a wire is moving in a magnetic field $B$, there is a Lorentz force acting on both the postive and negative charges, separating them to create an electric field, which is a great explanation to aid ...
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Alpha Particle moving through a magnetic field [closed]

How would I find the acceleration of an alpha particle moving through a magnetic field given the force of the magnetic field, the charge, the initial velocity and the strength of the magnetic field.
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How 7.0 Tesla can yield better image resolution with less teslas?

I am studying the book 7.0 Tesla MRI Brain White Matter Atlas 2nd edition by F. Calamante for 1.5, 3.0 and 7.0 Tesla images, respectively I do not understand how the image resolution can be greater ...
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Why are magnetic quantum numbers assigned like they are assigned in the paper on WS2 monolayers?

Now I'm reading the following paper: Sie, E.J., et al., 2015. Valley-Selective Optical Stark Effect in Monolayer WS2. ‎Nat. Mater., 14, 290-294 And they assigned magnetic quantum number to valence ...
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Magnetic force and torque for 2D neodymium ball simulator

I'm trying to write a simulator for neoballs. I'm doing only 2D for a start, in which each ball has a magnetic moment, m, that is in the x-y plane. The simulator will use time-step integration at 60 ...
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Will rotating magnets slow down one another when interacting?

Will rotating magnets slow down one another when interacting? Two discs are spinning. Both have separate magnets attached. Disc one has a diameter of $8~\mathrm{cm}$ and disc two has a diameter ...
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Is energy only transmitted through electromagnetic and particle radiations? [closed]

Which are the other ways of transmission if any? If energy does not require any medium for transmission(as for sunlight reaching earth, the heat too), is it transmitted in quanta in particle radiation ...
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Does the direction of magnetic field in a solenoid point from north to south anywhere? [closed]

Is there any case where the direction of magnetic field inside a solenoid points from its North Pole to its south?
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Possiblity for particle to be carried by a wave such as a photon or electromagnetic wave/waves in general for means of transportation/travel? [closed]

I am wondering whether it is possible for a photon/EM wave to carry a very small particle like an elementary particle or smaller on it like a highway carries a car traveling on the highway or an ocean ...
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What happens to a radar signal when it meets with a superconductor? [duplicate]

A radar system has a transmitter that emits radio waves called a radar signal, consisting of electromagnetic radiation. What happens when it meets with a strong superconductor, considering the fact ...
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Why can't diamagnetic and paramagnetic materials be magnetized?

Ferromagnetic materials can be made into permanent magnets. How come diamagnetic, and paramagnetic materials be made into magents? Does it have to do with the valence electrons, and how they are ...
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Find magnetic field of parabaloid-spiral particle path

Given the components of the particle's path (tcos(at), tsin(at), R(x^2 + y^2)), where a and R are constants, how can I find the magnetic force causing this? I would like to understand if this can be ...
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Charged Accelerometer in Orbit

It is well known that an accelerometer (or any other object for that matter) in a gravitational orbit will register nearly zero acceleration. According to this answer, this is because the object is, ...
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Landau quantization: degeneracy of first level

In some books the degeneracy of one Landau level in a two-dimensional gas of free electrons is calculated in the following way: Note: The electron spin is not considered. Number of states of a free ...
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Electromagnetic lifts, and work

Magnetic field doesnt do any work, so when an electromagnet lifts, say a car or something, where is the energy coming from?
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What is the physical meaning of Lorenz gauge condition? [closed]

What is the physical meaning of Lorenz gauge condition? And what part of the solutions we throw?
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A “figure-8” EM field created by a dipole antenna

This question pertains to the EM field of a Pulse W5017 dipole antenna. The data sheet of this antenna can be found here (which contains information regarding the radiation patterns). There are TWO ...
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Confusion regarding conductors and their behavior

Consider two thin plates and one thick plate(all conducting). A and C are the thin plates, B is the thick one. Now B is inserted between the parallel plates A and C. A is given a charge 2q and C is ...
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B field, reaction to magnetic medium

I've read 'if you put a magnetic medium into a conductor loop the B-field will change everywhere while if you put an electric charge into a dielectric sphere the dielectric sphere won't have any ...
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What would occur between the parallel plates of the capacitor?

In capacitors dielectric materials are sometimes inserted between the parallel plates. What would happen if a diamagnetic, or a paramagnetic material is inserted between the parallel plates of a ...
281 views

A contradiction between Biot-Savart and Ampere-Maxwell Laws?

I came across a problem that I cannot get my head around. Consider two very small spherical metallic balls given charges +Q and -Q. Assume that they can be approximated as point charges. Now, they ...
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Does a displacement current have to be included in the Biot Savart Law?

Consider two spherical balls given charges of equal magnitude and opposite signs. Now, we connect them with a conducting straight finite wire. A current will flow in the wire till the charges on the ...
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wiki says: Bremsstrahlung is electromagnetic radiation produced by the deceleration of a charged particle when deflected by another charged particle, typically an electron by an atomic ...
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How strong is Earth's magnetic field in space?

I've been searching around Google and Youtube about the strength of Earth's magnetic field. By the help of wikipedia, I have found out that it's magnitude is 25 to 65 microtesla or 0.25 to 0.65 Gauss ...
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Can the Hall effect drive a current?

In the Hall Effect current is passed through a wide strip of metal in a perpendicular magnetic field. Since (some of) the negative charges in the metal move but the positive ones stay put, the ...
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Good book to grasp physics [duplicate]

I'll try to be clear. I'd like to ask you if you know some books or chapters in textbooks which explaining the "meaning" of some physical phenomena or entities. I may try to be more specific using ...
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How to prevent magnetic field from generating in current carrying conductor?

Is there anyway to prevent generating magnet field or nullify it.
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Hamiltonian formulation of the semiclassical Model of electrons

I'm currently reading the book Solid State Physics by Neil W. Ashcroft and N. David Mermin. In Chapter 12 they introduce the "Semiclassical Model of Electron Dynamics". In short: After having solved ...