All Questions
Tagged with electromagnetism homework-and-exercises
258
questions with no upvoted or accepted answers
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Magnetic field due to circular surface current density
I am trying to find the magnetic field between two coaxial cylindrical shells of radius $a$ and $b$ respectively. They have a surface current density of $K = K_0cos(\theta)\hat{\theta}$ and $K=-K_0cos(...
- 324
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Capacitance of a thin conducting ring
I am following an exercise in which the capacitance of a thin ring is computed. The ring has radius $b$ and thickness $2a$ where $a<<b$.
In this exercise they compute the potential due to a ...
- 735
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When and how will charged oscillating pendulum in vacuum and Earth gravity stop?
Let's say there is a positively charged metallic sphere hanging on a thread in Earth's gravity and in vacuum. There is no electric field (except for the field from the sphere itself), no friction etc. ...
- 11
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Is the closed contour integral of the Lorentz's Force equal to charge * EMF of the circuit?
I have a situation as pictured
That is, a rotating rectangular spire subject to an uniform magnetic field $\vec{B}$ (The rods to which it is attached and make the system spin is non-conductive, so it ...
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Equations of Motion for Hidden Photon
I was reading a paper called Parametrically enhanced hidden photon search by Peter Graham et al. In the paper, a Lagrangian that describes the theory of the hidden photon is
$$\mathcal{L}=-\frac{1}{4}(...
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Magnetic field due to a line and a plane
I need to find the magnetic field produced by this arrangement
Let me explain the image: The vertical line is a conducting straight line with a current being conducted. Now, the horizontal line is ...
- 980
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35
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Two bar magnets taped together in opposite direction (north-south) dropped through a coil
I conducted an experiment where I have to align two bar magnets so that both ends are “north - south” and tape them together. Then, I have to drop them through the center of a coil of 400 turns
...
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Transformers: How does current in primary coil change?
I was doing a question on transformers and found this really confusing question:
A 100% efficient transformer converts a 240V input voltage to a 12V
output voltage. The output power of the ...
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Charge Moving in Field of Magnetic Dipole
I'm self-studying Kibble & Berkshire Classical Mechanics, and I'm completely stuck on Problem 11 in Chapter 12 on Hamiltonian mechanics.
It asks about a particle of mass m and charge q moving (in ...
- 81
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58
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How do I know if a solution of Maxwell Equations is caused solely by the charges?
My question is very general and it isn't limited to the system that I calculated the fields. I need a general answer or a particular answer for my problem. I found two fields $\mathbf E,\mathbf B$ ...
- 277
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What is the physical meaning of the definite integral of the superficial current density?
Studying the experiment of a magnet falling down through a copper tube, the problem gives me the graph of the surface current density, as a function of $x$, $x$ varying on the longitudinal axis of the ...
- 11
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Density of States (DOS) to energy graph
I am trying to find the amount of electrons in a conduction band in Si (Silicon), all I've got is a graph similar to this one:
I've tried to integrate like this:
$$ N = \int_{1}^{\infty} \frac{1}{1+\...
- 11
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3
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The electric field should be in circular coil. But why do current flows in whole circuit?
We know changing magnetic flux induces electric field which makes current to flow .here in the below picture the flux is changing through only circular coil bout not through the rectangular part.so ...
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What is the retarding force due to eddy currents
I am currently struggling to find an expression to approximate the retarding force due to eddy currents when a magnet moves along at a speed $v$ beside a long, straight and flat conductive plate made ...
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How does Schwinger transform a static $(\phi,0)$ to $(\phi ', A)$ in a moving frame?
Schwinger writes in his paper Electromagnetic mass revisited:
Any spherically symmetrical charge distribution of total charge $e$, at rest, is represented by the potentials
$$\phi \sim ef(r^2),...
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