All Questions
Tagged with electromagnetism homework-and-exercises
1,551
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Potential of an alternating electric field in a capacitor
My question comes from a problem of electrodynamics where there's a relativistic particle with a given 4-momentum ($p^\mu=(\varepsilon,\vec{p})$) which enters a capacitor with an alternating electric ...
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What would be the Joule requirement to a railgun launch a conventional bullet at mach 7?
The railgun project from the US Naval Surface Warfare Center Dahlgren Division shoots a projectile of 3.2kg at a speed of mach 7 with 18.4 megajoules of energy.
How many joules would a railgun need to ...
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Primary constraint of electrodynamics
I have some problems understanding the transition from the Lagrangian to Hamiltonian formalism of electrodynamics. I will use the metric $(-+++)$.
I want to start from the Lagrangian which is ...
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1
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Magnetic Scalar Potential of Infinite Wire
While working on a question about magnetic scalar potential, I encountered a challenge. The question posits that the magnetic scalar potential, denoted as $\phi$, takes the form $\phi = -\frac{I}{2\pi}...
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The origin of energy density formulas in Maxwell's electromagnetism
I am looking at the derivation of Poynting theory in Electrical Engineering texts and they usually start by the two statement:
$$W_e = \int_V\frac{1}{2}(\vec{E}.\vec{D})\,\,dv$$
$$W_m = \int_V\frac{1}{...
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Detailed derivation of the energy-momentum tensor from the Maxwell Lagrangian [duplicate]
I have started studying QFT, and I am currently reviewing briefly on the classical field theory. I have come across the Maxwell Lagrangian given by
$$
\mathcal{L}=-\frac{1}{4}F_{\mu\nu}F^{\mu\nu}.
$$
...
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Non-standard circuit
I partially solved this problem.
Problem: A charged sphere of radius $a$ is connected through a resistance $R$ to the earth. An electronic flow breaks out towards the sphere of infinity at speed $v$ ...
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Momentum conservation in charged particles scattering
I'm studying a problem involving the scattering of two charged particles, A and B, with a mass ratio of 1:4 and identical charges. The particles move towards each other with equal and opposite ...
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Finding the vector potential
$$\nabla\times\mathbf{B}=\nabla\times\left(\nabla\times\mathbf{A}\right)=\nabla\left(\nabla\cdot\mathbf{A}\right)-\nabla^2\mathbf{A}=\mu_0\mathbf{J}\tag{5.62}$$
Whenever I try to work this out and ...
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Why can the current in this region be represented as this formula?$I_{in}=I-I\frac{r^2-b^2}{c^2-b^2}$ [closed]
An air coaxial transmission line has a solid inner conductor of radius a and an outer conductor of inner radius b and outer radius c. Find $\vec B$ as a functions of radial distance r.
The region in $...
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Derivation of the ring charge from a disk charge with a hole
I am doing a problem in which I am given a uniformly charged disk, charge density $\sigma$, with radius $b$ and a concentric hole of radius $a$ in the $xy$ plane. A part of the problem I would have to ...
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Two balls are dropped from the same height. Ball A is metallic and B, made up of an insulating material. Which of them touches ground first? [closed]
General motion under gravity states that both of them reach the ground simultaneously. But here, ball B reaches first. I searched for the solution but couldn't find any. Does it have anything to do ...
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229
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How does the Lagrangian work with a magnetic field?
I was told the following Lagrangian is for a charged particle with spin moving in a constant magnetic field:
$$
L = \frac{\left ( \vec p \right ) ^2}{2m} + \vec \mu \cdot \vec B$$
Let's just say $B$ ...
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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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Does an emf in an aeroplane's wings result in a current? [closed]
In part (b) of this question, they have stated that the current that flows through the aeroplane is 0.00 A. When you use the value for emf from part (a) and the resistance, you can calculate that I = ...
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