All Questions
Tagged with electromagnetism homework-and-exercises
1,550
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0
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132
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Coilgun projectile force calculation
Please excuse me if I am completely wrong because I am a 9th grader but I hopefully am able to explain briefly about my problem. I was trying to create a function to calculate the Force of an iron ...
- 12.1k
1
vote
1
answer
57
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Path of a relativistic charge due to a (nearly) infinitely massive charge [closed]
Suppose we know the position, velocity of a charge at time $t=0$ and its rest mass is also known. It is attracted by a (nearly) infinitely massive known opposite charge which is at rest and always be ...
- 1,613
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34
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Is there a $H$-field formed by a uniformly moved, charged ball?
Imagine a charged ball with surface charges. Let it travel with a constant velocity $v$.
Imagine a point outside the ball. Since the charge is moving, there is a electric displacement displacement ...
- 207k
4
votes
2
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583
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Maxwell's equations with differential form formalism
I've been reading Sean Carroll's book on GR and I stumbled upon an exercise on EM using $p$-forms. I think I've solved the problem correctly but I am having problems with my answers. I'll provide the ...
- 6,695
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Field Momentum of a Toroid with a point charge at its center
I´ve been solving the following problem and I need some guidance. The problem asks to calculate all the components of the field momentum of a circular toroidal coil of mean radius a and N turns with a ...
- 12.1k
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3
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248
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Derivation of Maxwell's equations using Lagrangian formalism [duplicate]
Some time ago, I read in Landau's Theoretical Physics Course you could derive Maxwell's equations using the Lagrangian formalism, and I find this to be exciting. Unfortunately, I don't have access to ...
- 4,411
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3
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206
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Deriving continuity equation from 4-current of a charged particle
how can i check that following 4-current for a single charged particle
$$j^{\mu}(x)=qc\int d\tau u^{\mu}(\tau)\delta^{4}(x-r(\tau))$$
satisfies continuity equation $$\partial_\mu j^\mu = 0.$$
- 952
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2
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Electric charge and cylinder
An electric charge is distributed with a uniform volume density $\rho$ in a cylinder with a radius $R$ and an infinite length.
Our professor said the following: By symmetry, the electric field is ...
- 6,235
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22
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What is the relationship between the energy absorbed and reemitted by an atom?
What is the relationship between the energy absorbed and emitted by an atom with the model of Lorentz?
In the Lorentz model of an atom, we have that, using the effective cross-sections we might get ...
- 75
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1
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66
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Direction of propogation of a EMW [closed]
If let say i have an EMW given by- (Note the difference between $k$ and K)
B(x,y,z)=$B_0sin[(x+y)\frac{K}{√2}+wt]\hat k$
i got confused in 2 different outcomes when i wanted to find out the direction ...
- 207k
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1
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39
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Covariant derivative property
I am trying to demonstrate this propertie
$$
\not{D}^2= \mathcal{D}^\mu \mathcal{D}_\mu-\frac{i}{4}\left[\gamma^\mu, \gamma^\nu\right] F_{\mu \nu}
$$
where $\not{}~$ is the Feynmann slash, and $D_\mu ...
- 26.6k
1
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1
answer
49
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How can I estimate the force of an electromagnet?
I am doing an experiment on electromagnetism, basically I am just testing the pulling force of an electromagnet using a newton meter with a magnetic hook and seeing how the pulling force changes as i ...
- 206
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2
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302
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Canonical momentum of a 4-vector field
In a four-vector field theory,
we have a given Lagrangian:
$$\mathscr{L} = C_{1} (\partial_{\nu} A_{\mu}) (\partial^{\nu} A^{\mu}) + C_2 (\partial_{\nu} A_{\mu}) (\partial^{\mu} A^{\nu}) + C_3 A_{\mu} ...
CommunityBot
- 1
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2
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How to compute the resistance of a nonuniform cylinder with varying resistivity?
The generally quoted formula foe resistance is
\begin{equation}
R = \rho \ell/A
\end{equation}
some special cases are easy to solve. For example the case where the current flowing along the z-axis and ...
- 895
7
votes
1
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How much power would it take to stop a bullet with a magnet?
If a 7.5 gram copper-jacketed lead bullet (say, a 9x19mm Parabellum) was travelling at 360 m/s, how much power would it take to diamagnetically stop it in the space of one meter?
This question comes ...
