Questions tagged [electric-fields]
For questions that utilize the concept of electric fields (commonly denoted by the letter E), or for questions whose answers likely involve electric fields. More specific than the [electricity] tag, as questions about the phenomenon & theory of electricity do not necessarily involve the discussion of fields.
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How can electric fields be used to detect cracks in metals? [closed]
My physics teacher brought this up in a lecture and I am not exactly sure what he is saying.
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Can electric field be discontinuous?
"This is because of abrupt discontinuity of fields"
I have read this or similar sentences in many papers. I am bit puzzled. How and under what conditions electric field can be discontinous? ...
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How is energy stored in magnetic and electric fields?
We say that there is energy associated with electric and magnetic fields. For example, in the case of an inductor, we give a vague answer saying that an energy of $\frac{1}{2} LI^2$ is stored in the ...
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Meaning of the Poynting vector
In a book I am studying, the Poynting vector is defined as:
$$ \mathcal{P} = \mathbb{E} \times\mathbb{H} $$
and it is described the Poynting's theorem, that states that the flux through a surface ...
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What happens if you use a battery to charge up a capacitor fully, and then disconnect the battery, where does the charge 'go'?
The title says it all really, but I think that since the battery is disconnected there is now an 'open circuit'. I know that charge can only flow if the circuit is complete (closed).
But the part that ...
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How can photons have an electric field without having a charge?
I've been reading up on photons, and find myself puzzled by an element of them...
How can photons have an electric field without having a charge? Correct me if I am wrong but I believe electric fields ...
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Why is electricity not transmitted wirelessly?
Why is electricity not transmitted wirelessly such that we don't need to span cables on the earth's surface? As in: electricity is transmitted wirelessly from the power plant to the household.
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Divergence of $\frac{ \hat {\bf r}}{r^2} \equiv \frac{{\bf r}}{r^3}$, what is the 'paradox'?
I just started in Griffith's Introduction to electrodynamics and I stumbled upon the divergence of $\frac{ \hat r}{r^2} \equiv \frac{{\bf r}}{r^3}$, now from the book, Griffiths says:
Now what is the ...
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How can the electric potential be zero at a point where the electric field isn't, if that field can give a test charge kinetic energy?
Say we have 2 charges set up like above. Why is $V_3=0$ ?
I can understand mathematically that the scalars fields cancel out, but I don't understand it physically. If I place a positive charge in ...
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Is there an electric field around neutral atoms?
Even if the atom is neutral (equal numbers of protons and electrons), the electrons and nucleus form an electrical dipole, so there is still an electric field around them, even though the total charge ...
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Why is there an electric field around this closed electric circuit?
I have difficulty understanding the picture below. I can understand the green magnetic fields. But why is there an outside, red, electric field? Isn't the electric field guided entirely through the ...
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Electrostatic fields with straight field lines
This question is motivated by a student of mine. Is there a general characterization, or classification, of electrostatic fields whose field lines are straight? There are some obvious examples:
...
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Would a spinning, evenly charged sphere generate a magnetic field?
I could see how it would go either way.
On the one hand, there IS moving charge; on the other hand, it is not discernibly moving.
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If we remove all electrons from a conductor, how can the positive charge rearrange itself?
Explanations of conductors in electrostatics that I have encountered seem to describe positive charge spreading out, because you could say that lack of electrons can be thought of as abundance of ...
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Does the electric field have infinite range?
Fields are a theoretical concept which makes it easy for us to understand or imagine various things such as how forces act. We use electric field lines to show the strength of electric fields.
So if ...
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