All Questions
14
questions
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66
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Calculate Electric Field on the Z-axis from a finite charge wire
I've been trying to find the electric Field on the Z-axis from a non-uniform charge density line charge. The wire is placed on the z-axis from $z=0$ to $z=1$, $E=?$ at $z>1$ and $z<0$
$$
\rho =...
- 1
0
votes
0
answers
63
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Electric field flux proportional to the field lines generated by (for example) a static charge
Suppose we have a stationary positive charge at a point in space that we call $+Q$. We know by definition that the flow of the electrostatic field is given by, in its simplified form,
$$\Phi_S(\vec E)=...
- 7,792
1
vote
1
answer
93
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Distance becoming equal to displacement
Consider a charged particle of charge q and mass m being projected from the origin with a velocity u in a region of uniform magnetic field $\mathbf{B} = - B \hat{\mathbf{k}} $ with a resistive force ...
- 333
4
votes
1
answer
158
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Properties about an elliptic integral of the first kind.
In polar coordinates, the electric potential of a ring is represented by the next relation
$$
\frac{\lambda}{4\pi\varepsilon_0}\frac{2R}{|r-R|}\left( F\left(\pi -\frac{\theta}{2}\Big|-\frac{4 r R}{(r-...
- 51
1
vote
0
answers
35
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Deriving force between continuous distributions of two volume charges without using infinitesimals
We know that force between two point charges is:
$$\vec{F}=k\ q\ q'\ \dfrac{\hat{r}}{r^2}\tag1$$
From here how shall we derive the equation for force between continuous distributions of two volume ...
- 1,141
4
votes
2
answers
118
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Can a small change to the magnetic field result in infinite changes to the vector potential?
Consider a magnetic field, $\mathbf{B}(x,z)$ given by
$$\begin{aligned}
\mathbf{B}(x,z) &= [B_x(x,z),\ B_y(x,z),\ B_z(x,z)] \\
&= \left[-\frac{l}{k}\cos(kx),\ -\sqrt{1-\frac{l^2}{k^2}}\cos(kx),...
- 1,027
1
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0
answers
91
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Examples of 2nd Order Differential Equations in Electromagnetism
I am looking for examples of second-order ODE's that are similar to the spring, and pendulum, as well as the LRC, LC, RC, and LR circuits and involve electromagnetism. I know how to solve them, and I ...
- 2,653
0
votes
1
answer
130
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Gauss's law in infinite space
Consider an infinite $3$D space with a charge density $\rho$ and a resulting electric field $E$.
Imagine $\forall (x,y,z)\in \mathbb{R}^3, \rho(x,y,z) = \rho_0$(a non-zero constant). In this case, ...
1
vote
1
answer
292
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How to show that $E_\theta=-\frac{\partial V}{r \partial \theta}$
How to show that $$E_r=-\frac{\partial V}{\partial r}$$ and $$E_{\theta}=-\frac1r \frac{\partial V}{\partial \theta}$$
where V is the potential at the point $(r,\theta)$ of the dipole.
I can take ...
- 1,164
0
votes
1
answer
476
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Derivatives interpreted as fractions [duplicate]
So I was wondering if manipulating differential as fraction is fine.In Physics problems ,usually, what I see is if we have equations of magnetic field ,we consider a magnetic field caused by a small ...
0
votes
1
answer
765
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Calculate change in radius for some change in electrostatic potential energy.
A sphere of radius $R$ has a charge $Q$ distributed uniformly over its surface. How large will a sphere that contains $90\ \%$ of energy stored in electrostatic field of this charge distribution.
...
user312097
1
vote
1
answer
1k
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How to derive resistance as a function of time to keep current constant in circuit?
Having found this answer to an electronics question, a subsequent question would be; in a primitive circuit having only one voltage source or sink in series with a resistor $R$, charging a capacitor, ...
- 26.1k
1
vote
0
answers
285
views
area of arbitrary surface element
I am a physics student with a minimal background in differential geometry and I am trying to determine an area element on an arbitrary surface. Suppose we have a surface parameterized by a function $z=...
- 377
1
vote
2
answers
4k
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Calculating the electric field of a disk
I'm having trouble regarding how to calculate the electric field of a disk. Here's the scheme:
The exercise states that the disk is uniformely charged. This is what I did:
Density charge : $\sigma = ...
- 367