3
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Does cutting out the surfaces with no surface charge affect the charge distribution on the remaining parts of a conducting surface of arbitrary shape?
Removing the uncharged parts of a charge distribution would not change the field configuration elsewhere. To show this, start with the Poisson equation (assuming the permittivity $\epsilon_0$ is the ...
- 936
2
votes
Why is my idea of voltage drop wrong?
To simplify matters, assume that the mobile charged particles under consideration are positive and ignore the thermal motion of the charged particles.
I am going to compare the motion of a charged ...
- 97.9k
2
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Why is my idea of voltage drop wrong?
Voltage drop means voltage loss, typically in the context of electrical current flowing through a series of resistors or a piece of resistive wire. Let's say we have a loop of resistive wire leading ...
- 95.5k
2
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Accepted
Understand power rating in layman terms
You stated that when one coulomb of charge passes through the bulb then $220\,\rm J$ of electrical energy is converted into heat and light.
This is a correct statement but you must now realise that it ...
- 97.9k
2
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Accepted
How do I compute the voltage accross a cell membrane given microstate of neuron (distribution of charged ions)?
The typical textbook start is the Nernst equation, which gives the reversal potential for a ion species. That is, is the electric potential that balances a given concentration gradient:
$$E_{rev}=\...
- 32.9k
2
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Accepted
Does the geometric shape of the cross-section of an infinitesimally thin conducting charged thread (wire) affect its electric field?
I assume the charge is uniformly distributed around the major radius for all these tori.
You are right. Shape and conductivity make smaller and smaller differences as a torus approaches a thin ring.
...
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1
vote
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A capacitor partially filled with dielectric
For some background, let's remind ourselves that the electric field is a conservative field. Because of this, we can define potentials that are independent of the particular path of integration. So ...
- 2,697
1
vote
Accepted
Electrostatic potential outside of a charged ball
Starting from the general form of the electrostatic equations $$\begin{align}\mathbf{\nabla} \times\mathbf{E}(\mathbf{r})&=0 \tag{1} \label{1}, \\[5pt] \mathbf{\nabla} \cdot\mathbf{E}(\mathbf{r})&...
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Accepted
Visualization of resistance
What does a resistor do in an electrical circuit?
The resistance of a conductor limits the amount of current that can flow in the conductor for a given potential difference.
I have been told to ...
- 73.7k
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Visualization of resistance
I have been told to think of water flowing in a pipe and which has a narrow part
I don't think the narrow pipe is a good analogy of a resistor.
In simple fluid dynamics the water in the narrow part ...
- 56.4k
1
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Voltage: work to move a charge, or difference of electric potential?
In the diagram below the red dashed circle with the negative charge at its centre is an equipotential with the electric field lines produced by the negative charge at right angles to the circle.
As ...
- 97.9k
1
vote
Accepted
Voltage: work to move a charge, or difference of electric potential?
it will take work to move the positive charge from point A to point B, as I must counteract the vertical component of the electric force and so on.
You are quite correct that the distance to the ...
- 358k
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