All Questions
Tagged with electromagnetism homework-and-exercises
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Topic : Classical Electrodynamics; Lienard wiechert potentials [closed]
So I have just finished studying the Lienard wiechert potentials for a moving charged particle. After doing some problems from Griffiths I stumbled upon some problem which as follows:
An ...
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Concerning railguns and magnetic fields
I'm part of a group working on a Physics II project based on electromagnetism, and my group decided to create a proof-of-concept railgun, shown here:
https://doityourselfgadgets.com/2013/10/homemade-...
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Magnet layout to maximize magnetic attraction along entire surface
We want to use permanent magnets to attract iron filings. For this, we have several neodynium magnets shaped as disks and we would like to lay them out to have the highest possible attraction along ...
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Should a wire loop moving through a constant rectangular magnetic field directed perpendicular to it's motion have zero induced current in the middle?
Suppose we have a loop of copper wire moving perpendicularly through a constant finite rectangular magnetic field directed into the screen .
When the loop enters the field, the induced current would ...
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Expression for change in orbital magnetic dipole moment
So, the question I attempted to answer from a physics textbook runs something like this:
"An electron is moving in a circle with radius $r$ and it has a mass of $m$. An external uniform magnetic ...
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How to calculate pole strength for this magnet?
I know magnetic mono poles don't exists and a magnetic poles always have equal strength. But what about a magnet which looks like this?
This is picture of magnet whose thickness is constantly ...
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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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Force acting on an infinite wire with current inside a magnetic medium
I've recently stumbled on an electromagnetics problem that I don't quite understand.
There is an infinite wire carrying current I that is placed inside a medium with magnetic permittivity μ1. At a ...
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Motion of a magnet inside a solenoid
I have a homework problem where a bar magnet is placed halfway inside a horizontal solenoid. A cut away shows that the magnet's north pole points to the left of the page and the south pole is outside ...
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Magnetic field of coaxial cylindrical capacitor
I have a coaxial cylindrical capacitor as shown, with inner radius a and outer radius b.
The potential difference across both cylinders is V. I need the magnetic field everywhere when the inner ...
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Location of high and low potential points in motional emf
Okay so in the above image the semi circular loop is rotated and a sector of it is introduced into the magnetic field.
Questions:
I know the magnetic field is constant so no non conservative ...
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Finding equation of motion of Lagrangian density: What does the location of the indices mean?
We are given the following Lagrangian density:
$$\mathcal{L}=F_{\mu \nu} A^{\mu} \mathcal{J}^{\nu}$$
where $F_{\mu \nu}$ is the electromagnetic field tensor, $ A^{\mu}$ the 4-vector of the vector ...
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How to find the mixed tensor, contravariant tensor and tensor trace of $F$?
I have a question in particle physics that ask me to find the mixed tensor, contravariant tensor and tensor trace of $F$:
Our professor didn't teach us that much about the math of tensor, which makes ...
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Fall of a square conductor loop perpendicular to a homogenous magnetic field
This is my homework. I am not asking you to complete it for me - I just need a push in the right direction so I can complete the rest. The question is translated from German, so it reads a bit awkward....
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Self-inductance of a finite solenoid
Where did the $l$ in the denominator come from? I am talking about the $l$ in muNI/2l[...]?
I can't match LHS and RHS.
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What book should I read to learn about the magnetocaloric effect
I am trying to study the magnetocaloric effect for a project but I can't find any good resources that deeply talk about it.
Could you make any good recommandation to learn the basics about this effect ...
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Magnetic moment of a paramagnetic cylinder
I am currently struggling with a problem where I have to calculate the magnetic moment $M$ of a
cylinder of radius $R$ and height $h$ made up of a paramagnetic material (aluminium) and under a ...
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Vector potential of Weird loop
I have to calculate the vectorpotential of a current flowing through the loop at the origin:
where the current is given by $I(t)=kt$ for some $k>0$.
Given equations
$$\mathbf{A} = \frac{\mu_0}{4\...
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Why is charge $q$ chosen as the variable of integration when converting from summation to integral form in electric field calculations?
If we have several point charges $q_1, q_2, q_3, \cdots$, and their distances from a test charge $Q$ are respectively ${\imath}_1, {\imath}_2, {\imath}_3$, $\cdots$, then the electric field intensity ...
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Doubt On Maxwell's Stress Tensor [closed]
I was reading Introduction to Electrodynamics by D.J. Griffiths, Chapter 8 Conservation Laws, Maxwell's Stress Tensor. The starting lines are the following:
Let's calculate the total electromagnetic ...
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Current sensitivity in transformer scheme with SQUID
I've tried to determine the maximum current sensitivity in this transformer scheme but I'm not sure if my solution is valid. I need to find the relation between the current in the input transformer ...
- 207k
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How to derive $\partial^{\nu}F^{\mu\alpha} + \partial^{\alpha}F^{\nu\mu} + \partial^{\mu}F^{\alpha\nu}=0$ for the Electromagnetic field tensor? [closed]
The problem says to show that
$$\partial_{[\mu}F_{\alpha\nu]}=F^{\mu\alpha, \nu} + F^{\nu\mu,\alpha} + F^{\alpha\nu,\mu}=0$$ stems from Maxwell equations.
I haven't been able to find this anywhere on ...
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Where am I going wrong when obtaining the Hamiltonian density for the electromagnetic field?
I'm trying to verify that the Hamiltonian density for the classical electromagnetic field is equal to the energy density. But the electric field is disappearing and only the energy density of the ...
- 207k
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Magnetostatics or dynamics?
A spherical conductor, carrying a total charge $Q$, spins uniformly and very rapidly about an axis coinciding with one of its diameters. In the diagrams given below, the equilibrium charge density on ...
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How do Relativity explains electromagnetic induction in the case of changing $\bf{B}$ with both loop and magnet at rest?
Here is how Griffiths lists the experimental evidences of electromagnetic induction.
Case 1 can be explained with Lorentz Force. I understood how Special Relativity relates case 2 to case 1, ...
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The magnetic field due to wire from infinity to 0 that expands isotropically on the plane $z=0$
An intensity current I descends down the $z$-axis from $z = \infty$ to $z = 0$, where
it spreads out in an isotropic way on the plane $z = 0$. Compute the magnetic field.
To begin this problem I ...
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Question about Fourier-coefficients in Griffith's Problem 3.15 (Electrodynamics) [closed]
I am having some trouble with problem 3.15 from Griffith's Electrodynamics. It states the following:
A rectangular pipe, running parallel to the $z$-axis (from $-\infty$ to $+\infty$), has three ...
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General Form of the Biot-Savart Law for anywhere on the $x$-Axis [closed]
This question is beyond me, and I have very little direction for solving it. I understand that the component of $\ B $ perpendicular to the $x$-axis is 0, and that the component parallel along the $x$-...
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Electric potential infinite box
I have a question about separation of variables to calculate the electric potential.
In the picture below the potential is only on the top of the box, which is infinite in the $z$-direction. What are ...
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Need help identifying missing boundary condition in charge transport problem
The system I am considering consists of a conducting liquid sandwiched between two electrodes.
The electrodes supply a constant flux of electrons $J_{ext}$.
In the liquid there are also uncharged ...
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