Electrostatics is concerned with the electrical fields and scalar potentials of stationary electrical charges and charge distributions. Use this for questions about electromagnetic situations in which currents and magnetic fields are absent, otherwise use [tag:electromagnetism] and/or ...

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Why isn't there a centre of charge?

When determining the gravitational attraction between 2 solid bodies, we can simplify computations by taking their masses to be concentrated at their respective centres of mass. However, had they been ...
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Balloon rubbing; where do the electrons go?

If you rubbed a balloon with a towel, where would the electrons go: the balloon or the towel? Why? I'm guessing the electrons would go to the object with a larger mass, but it's just a guess. :)
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In Method of images type problems, why isn't the induced charge taken into account while solving it via Green's functions?

To take the simplest example, $$\Phi(\vec{r}) = \begin{cases} V & r\leq a \\ 0 & r\geq a \end{cases}$$ For a plane conducting surface that extends all the way. Choosing an appropriate ...
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2answers
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What is the effect of temperature on electrostatic-gravitational balance?

We have two identical massive metal spheres at the same temperature at rest in free space. Both have an identical charge and the Coulomb force [plus the black-body radiation pressure if the ...
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What prevents the accumulation of charge in a black hole?

What prevents a static black hole from accumulating more charge than its maximum? Is it just simple Coulomb repulsion? Is the answer the same for rotating black holes? Edit What I understand from ...
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Paradoxical interaction between a massive charged sphere and a point charge

Suppose we have a sphere of radius $r$ and mass m and a negatively charged test particle at distance d from its center, $d\gg r$. If the sphere is electrically neutral, the particle will fall toward ...
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4answers
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Resistance between two points on a conducting surface

Suppose we have a cylindrical resistor, with resistance given by $R=\rho\cdot l/(\pi r^2)$ Let $d$ be the distance between two points in the interior of the resistor and let $r\gg d\gg l$. Ie. it is ...
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2answers
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Why two objects get charged by rubbing?

It is always told as a fact without explaining the reason. Why do two objects get charged by rubbing? Why one object get negative charge and other get positive charge?
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1answer
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Electric Field for a hollow sphere with point charge

I think I am over thinking this question: A point charge of $-2\space\mu C$ is located in the center of a hollow sphere. The internal and external radius of the sphere is given by $6.5$ and ...
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2answers
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What is the net charge of the Earth?

This question arose in a seminar today about the solar wind... This is my vagueish understanding of the problem - please correct if you see errors! The 'classical' picture of atmospheric electricity ...
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4answers
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Method of Images

The method of image charges is a well-known and very useful tool for solving problems in electrostatics. Unfortunately, when I was taught this method, it was presented simply as an algorithm. No real ...
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3answers
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Charge density in concentric spheres

Question: If there are two conducting spherical shells and the inner shell is grounded, what will be >the charge density in the inner shell if there is a charge Q placed on the outer shell? ...
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2answers
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Virtual photon description of B and E fields

I continue to find it amazing that something as “bulky” and macroscopic as a static magnetic or electric field is actually a manifestation of virtual photons. So putting on your QFT spectacles, look ...
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energy field of a newly created particle

The question is: How to calculate the energy of electrostatic field of a newly created particle. The usual formula involves integration 'all over space'. According to GR I believe that 'all over ...
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1answer
316 views

Couch shocks everything!

How do I get rid of the static charge I get from my microfiber couches? Every time I get up and touch something it zaps me... I'm mostly worried about my laptop getting fried.
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3answers
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Coulomb force in SI and cgs

Coulomb force in SI is $ F = \frac{Q1*Q2}{4\pi\varepsilon R^{2}} $ while in CGS $ F = \frac{Q1*Q2}{R^{2}} $ why is it? I mean doesn't it any make difference in dimension? since $ \varepsilon $ ...
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Why does dust stick to rotating fan propeller?

Why does dust stick to rotating fan propeller? Intuitively, most people (including I) think of the dust will not stick to rotating fan propellers. EDIT 1: Thank you for the great explanations. I am ...
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5answers
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Does Coulomb's Law, with Gauss's Law, imply the existence of only three spatial dimensions?

Coulomb's Law states that the fall-off of the strength of the electrostatic force is inversely proportional to the distance squared of the charges. Gauss's law implies that a the total flux through a ...