Electrostatics is concerned with the field and potential of stationary electrical charges and electric charge distributions. Problems are this type are almost exclusively concerned with mathematics of geometries using the inverse-square law.
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How is Gauss' Law (integral form) arrived at from Coulomb's Law, and how is the differential form arrived at from that?
On a similar note: when using Gauss' Law, do you even begin with Coulomb's law, or does one take it as given that flux is the surface integral of the Electric field in the direction of the normal to ...
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1answer
105 views
How does one come up with the Coulomb's law?
My teacher mentioned that field line density = no. of lines / area and the total area of a sphere is $4\pi r^2$ and so an electric force is inversely proportional to $r^2$. Actually, why can the total ...
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215 views
Electrostatic Dust Removal
I have been recently reading a paper on dust removal and I have a few basic questions regarding it.
First off, I am citing this paper - "Dust removal system with static electricity"
Basically, an ...
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107 views
How do I find the force on the charged sphere due to a dipole sitting inside?
I have a dipole sitting inside a charged sphere i.e. at the centre of the sphere. As far as I can see the force on the Dipole is zero because the external electric field on the dipole at $r=0$ is $0$. ...
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What equation describes the electrostatic potential in these circumstances?
I have a solver for Poisson's equation and it works nicely. It uses finite differences. It works in the presence of multiple dielectrics.
It also solves the Poisson Boltzmann equation. That is, fixed ...
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1answer
426 views
The formula of the force exerted on an electric dipole by non-uniform electric field
When an electric dipole of moment $\mathbf{P}$ is located in a non-uniform electric field $\mathbf{E}$, there is an net force exerted on it.
However, the formula of the force in some books is read ...
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2answers
505 views
How does rubbing cause the transfer of electrons from one object to the other? [duplicate]
I have just learnt about electrostatics. Why would there be a transfer of electrons? Is it because of the difference of the materials (i.e. triboelectric series)? So in the case of two different ...
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296 views
Are the Maxwell's equations enough to derive the law of Coulomb?
Are the 8 Maxwell's equations enough to derive the formula for the electromagnetic field created by a stationary point charge, which is the same as the law of Coulomb?
If I am not mistaken, due to ...
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2k views
Why is electric field zero inside a hollow metal sphere ?
The figure below shows a hollow metal sphere with a positive point charge $Q$ sitting outside it. What is the electric field at the center of sphere ? The answer is zero (look at here at the beginning ...
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137 views
How will water affect the electric field?
How will 2 charged bodies act when the separation medium between them is water ?
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2answers
212 views
Find the quantity of charge - given potential function
A potential function is given by $V(r)=\frac{Ae^{-\lambda r}}{r}$ Find charge density and hence charge.
I first took the gradient of potential to get $\vec{E}(r)=\frac{Ae^{-\lambda ...
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45 views
outward pressure in an confined electron gas
Suppose i have some electrons stored in a empty shell container with a negative ion layer in the inner surface so the electrons keep bouncing inside without being able to leave the inner cavity.
I ...
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2answers
277 views
Proof of charge existence on a grounded conductor
A question regarding the existence of charge on grounded conductors is confusing me.
Could there be charge on a grounded conductor?
How does this not contradict Gauss's Law?
Since every conductor ...
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0answers
69 views
Subtle problem on capacitors [closed]
Imagine we have 2 capacitors of capacitance $C_1$ and $C_2$ respectively. One is charged with charge $Q_1$, and the other is not charged.
Now we connect them in series as shown in figure:
What is ...
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2answers
348 views
electric potential at center of uniform electric field
it is said that the electric potential at the center of uniform electric field is zero.
my question is that why is it zero?
electric potential is the work done per unit charge.
$V = W/q$
and this ...
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611 views
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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2answers
842 views
Why is electric field strong at sharp edges?
I learned about the coronal discharge, and the common explanation is because the electric field is strong where radius of curvature is small. But I haven't found anything yet that explains why ...
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1answer
108 views
Will the plates of a parallel plates capacitor keep its charge after being charged then seperated from the non- conductor?
If i had 3 plates 2 metals and 1 glass .I put them together to form a basic parallel plates capacitor.
After charging it and approaching it to an electroscope nothing happened that's because ...
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3answers
129 views
Where does the energy for repulsion in charges come from?
If I bring together 2 objects with the same charge, they repel. But even after the repulsion has taken place, there is no loss of charge in the objects. Where does the energy come from then?
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2answers
197 views
Are electrons on a conductor, in electrostatic equilibrium, stationary?
Electrostatics basically means dealing with time independent electric fields (which was produced by stationary charges)
Now consider a neutral conductor. We know that putting a net negative charge on ...
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2answers
147 views
Energy in electric field
I'm having some trouble understanding a homework question and would appreciate some help.
The question is as follows:
Jenny charges a capacitor with the help of a battery. She then removes
the ...
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3answers
470 views
Field due to current in a wire
Suppose a current flows in a straight cylindrical wire so that an electric field $\textbf{E}$ is maintained in the wire.
Will there be an electric field just outside the wire..?
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1answer
758 views
Potential Gradient & Electric field…
Potential gradient is the negative of the electric field. Does the negative (here) means that its direction is opposite to electric field.?
If it does mean this, How is the direction of the ...
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1answer
173 views
Why is water not used as a dielectric in the condenser?
The dielectric constant of water is very high. Then why is it not used as a dielectric in the condenser?
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1answer
80 views
Static electric charge
When some materials are chafed one to another, they obtain opposite electric charges. Does it mean that if these materials will then be connected to the ground, the direct currents of opposite ...
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1answer
428 views
Is the electric field at the edge of a uniformly charged disk infinite?
Consider a disk with a radius $R$ (I'll use $R=1$ at various points here) that has a constant surface charge density $\sigma$. Unlike the similar problem of the field in the vicinity of a infinitely ...
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3answers
925 views
What are the applications of Gauss's law in technology? [closed]
Freshmen physics textbooks use Gauss's law plus symmetry to calculate the electric field.
I was wondering if this method of finding the electric field using a symmetry is used in real applications in ...
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4answers
2k views
Infinitely charged wire and Differential form of Gauss' Law
I have tried calculating the potential of a charged wire the direct way. If lambda is the charge density of the wire, then I get
$$\phi(r) = \frac{\lambda}{4 \pi \epsilon_0 r} \int_{-\infty}^\infty ...
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1answer
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The Ultimate Hand Dryer
I have come across many hand dryers that attempt to dry your hands really fast after you wash them. Here are two of them:
XLERATOR
http://www.exceldryer.com/
Dyson Airblade
...
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0answers
136 views
A crazy problem
Easy
Consider the following figure
Each red point is a particle of a known mass that carries charge Q/2 and connected to a the box by a thread of known length. This problem can be solved easily to ...
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1answer
207 views
Calculating dust attraction to a charged surface
Even though dust particles are neutral, they tend to be attracted to a charged surface. I am guessing this is due to charge induction.
Is there a way I can compute the attraction? how will it vary ...
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2answers
185 views
Shape of electric charges on sphere in equilibrium state
When electric charges of equal magnitude and sign are released on a regular sphere (and assume that they stick to the surface of the sphere, but they are free to move along its surface), what is the ...
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2answers
212 views
Scale invariance symmetry as a simple argument in an electrostatics problem
In the comments to this post, it was hinted that proving that the force acting on a charge at a vertical distance from a uniformly charged plane is independent of that distance can be done by ...
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3answers
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Change in attraction of charged bodies
If I insert a piece of glass between two objects carrying different charges, would they still attract?
If they attract, does the piece of glass affect the force of attraction and is there any formula ...
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2answers
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Will the positive ions in an aqueous solution be attracted to a charged body ?
If I had a negatively charged body , say an electret , and i put it in a container of NaCl solution . Will the positive ions of sodium be attracted to it ? and why? If no, why do the positive ions ...
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2answers
332 views
How do electrons repel?
I understand the basics, protons have a positive charge, neutrons have no charge, and the electron has a negative charge. But looking at the lines of force from a proton, they flow outward and push ...
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1answer
125 views
If I had 2 charged bodies attracted to each other when i move one , will the other move too? [closed]
Does the force of attraction between them have to be higher than a certain number to be able to move with each other?
How will the weight of the objects influence the process?
Will they be moving with ...
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2answers
120 views
Task with three metal plates [closed]
There are three parallel metal plates. Two boundary plates are fixed and connected with a galvanic battery, maintained a constant potential difference $\Delta \varphi$. Middle plate was initially in ...
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3answers
401 views
Will two magnets lose magnetism if they stick to each other for infinitely long time?
Here we have two magnets and they are sticking to each other. What I've learned that could possibly explain it is one magnet holds positive charge and the other one holds negative. But when the ...
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1answer
175 views
Capacitance and Light Bulb And Dielectric Slab [closed]
An electric lamp having coil of negligible inductance connected in series with a
capacitor and an AC source is glowing with certain brightness. How does the
brightness of the lamp change on reducing ...
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2answers
2k views
Why do grapes in a microwave produce plasma?
Some of you may know this experience (Grape + Microwave = Plasma video link):
take a grape that you almost split in two parts, letting just a tiny piece of skin making a link between each half-part.
...
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0answers
138 views
A square with electric field lines parallel to its sides [closed]
A square ABCD has charges $+q$ and $-q$ on the vertices A and C (diagonally opposite sides). How can I place point charges outside this square so that electric field lines are parallel to all the ...
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2answers
333 views
Capacitors in series
I need some explanations on the green underlined sentences.
1) "Must continue to have zero net charge..." What if the $\ C_2$ had +2Q on the left plate and -Q its right plate? The net charge ...
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2answers
144 views
Is it really to solve problem below by using, in the main, Gauss law?
There is an infinite cylinder surface which uniformly charged along and has a surface charge density, which can be represented as
$$
\sigma = \sigma_{0}cos(\varphi ),
$$
where $\varphi$ - polar angle ...
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1answer
194 views
Find the distance of a third charge [closed]
The problem I am having is:
Two positive charges (+8.0 mC and +2.0 mC) are separated by 300 m. A third charge is placed at distance r from the +8.0 mC charge in such a way that the resultant electric ...
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1answer
148 views
difference between battery and capacitor in urdu languege [closed]
Heading
List item
List itementer code here
Blockquote*emphasized text*
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1answer
147 views
Why do hydrogen atoms attract?
That is, why is the potential energy with the orbitals overlapping less than with the Hydrogen atoms 'independent'.
Similarly, why is a noble gas configuration stabler than if an electron were to be ...
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1answer
77 views
Fields of Steady Currents Using Electrostatics
Suppose you have a uniform ring charge rotating at constant angular velocity so that you also have a uniform ring of steady current, and thus you can use the Biot-Savart Law to compute the magnetic ...
