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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Which was the first Coulomb's constant value? [closed]

Which was the first Coulomb's constant value? I didn't found any info in the Internet. I need the first value of K to compare it with my experiment. Could you please help me?
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1answer
747 views

Apply Gauss' law to find electric field around nonconducting plastic sheets [closed]

The question: Two very large, nonconducting plastic sheets, each 10.0 cm thick, carry uniform charge densities $\sigma_1$,$\sigma_2$,$\sigma_3$ and $\sigma_4$ on their surfaces, as shown in the ...
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2answers
41 views

Electric Potential of Point Charge (sign problem)

This question has been asked before, but the answers didn't clarify the problem for me, so I thought I might ask again. It's really a simple question. Let's say we're calculating the electric ...
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1answer
47 views

Equivalent DC circuit with charged conductors

I am trying to find equivalent circuit for a circuit composed of interconnected capacitors when isolated pieces of conductor may carry nonzero electric charge, and I have been struggling with this ...
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4answers
10k 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
78 views

Disturbing a line of infinite alternating charges

Consider a line of infinite number of alternating charges. All are point charges having charge of same magnitude and are placed in a line. Neglect the effect of gravity here. Consider one of the ...
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1answer
11k views

Electric field due to an electric dipole at a point on the equatorial line

According to [tamilnadu][1] textbook Electric field due to an electric dipole at a point on the equatorial line is given as The direction of E is along ...
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0answers
13 views

Pearson correlation of neural responses with it's linear estimation

I am trying to anderstand the following fact: Suppose I have a linear estimation of a stimulus: $ \hat{s} = \mathbf{w}^T(\mathbf{r} - \mathbf{f}(s_0)) + s_0$ where $\mathbf{w}$ is a vector of ...
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1answer
23 views

Maltese Cross Tube and the anode

I understand that Sir William Crookes' Maltese cross tube shows that cathode rays travel in a straight path but I am unsure of why the cathode rays aren't affected by the anode as there is an ...
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1answer
95 views

What is the proof for Gauss's law? [duplicate]

What is the proof for Gauss's law? Can you give me some explanation and details with the proof?
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1answer
34 views

Why potential at infinity is 0? (sphere of constant electrostatic potential)

Suppose I have a sphere of radius $R$ with potential $V_o$. Since the volume inside the sphere is bounded, then the lack of curvature of the potential (i.e. $\nabla^2\phi = 0$) gives a potential ...
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2answers
69 views

How can the fact that there is no electric field inside a hollow conductor be explained by Faraday's ice pail experiment?

Basically something very similar to these pictures These are from two separate books. The bottom picture says that all the excess charge in an object can be transferred to an already charged metal ...
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1answer
56 views

Electric field's area [closed]

How much area an electric field surrounds? since we're just able to draw the electric lines of force we sometimes think that the field is though 3d but surrounds a finite area. But is it measurable or ...
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0answers
9 views

Discharge Static Electricity from Carpet without chemicals

I've got a large amount of static electricity built up in a room. Is there any way I could discharge the static without the use of chemicals?
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0answers
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Why x-axis E field exist in Electroosmosis Example

The explanation in Wiki said it is because the surface charge will induce electrical double layer at top and bottom surface, so that if we apply x direction E field, there will be a flow between two ...
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2answers
343 views

Gauss's law… if the integral defining $\boldsymbol{E}$ diverges?

I have been told (here) that, under particular conditions, the electric field produced by a charge present in space $D$, defined by ...
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2answers
36 views

Calculation of electric potential in Geiger-Müller tube [closed]

We are given a cylindrical rod with linear charge density $λ$, and a coaxial cylinder with linear charge density $-λ$, as shown in the picture. We are to show that the potential difference between ...
4
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2answers
193 views

Why in electrostatics is $dV=-E.dr$ but in electromagnetic induction, $EMF=+E.dS$?

In electrostatics we learned that $$dV=-E.dr$$. I understood the derivation which was used to derive this. Now when I have come to Electromagnetic Induction,I see that when there is a time varying ...
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2answers
49 views

Induced charges

Consider a charge +q placed inside a cavity of conducting body. Charges will be induced as shown in the diagram below. How do we show that the electric field at a point A inside the cavity due to ...
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1answer
35 views

Capacitance of Nested Spheres

Imagine that we have two nested spheres and I wish to calculate the capacitance. First of all, I'm able to do the calculation. What I'm confused about is how it is possible for the Electric Field to ...
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3answers
40 views

What is the field near a sphere of charge, with opposite charge inside?

This is a question from my high school physics class years ago. I'm embarrassed to say I still don't understand the answer. Say we have a non-conducting (like garnet) spherical shell, with -1 C ...
5
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2answers
149 views

Why resistivity of copper wire is not zero even at zero kelvin?

At zero kelvin, everything seems dead stop. There is no movement occurring at zero kelvin, even at atomic level. As there is no movement in atoms, there is no vibration of atoms about their mean ...
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1answer
1k views

Why does Gauss's law work for a charge off center in a spherical surface?

CASE 1: Consider an enclosed spherical surface with a charge $q$ at its centre. From Gauss' law we can say that the flux through this sphere is $q/\epsilon_0$. CASE 2: The charge is inside but off ...
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1answer
32 views

What are the clicking sounds when static electricity occurs?

Sometimes, when there's static electricity, soft clicking sounds can be heard. This may happen when two fabrics are rubbed or when you get a static shock. What exactly causes this sounds?
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1answer
25 views

Dipole-dipole field

Assuming that we have two parallel and exactly identical electric dipoles. How does bringing them together change their frequency? What would such field look like (how would they interact)? In fact, ...
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2answers
56 views

Equipotential surface paradox

Consider a point charge +q as shown below. Now consider a equipotential surface and two points in it A and B. now the potential at A is equal to potential at B. If we now integrate (E.ds) from A to ...
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2answers
54 views

What does the movement of charge in an object mean?

When it is said that charge "moves" throughout an object, like if negative charge moves to the edge of an object and the charges become polarized, does this mean that the electrons has moved to the ...
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2answers
22 views

Electric fields and potential

E = electric field V = electrostatic potential r = distance ' = derivative E = - (V)' therefore if E increases V decreases Also if r increases E decreases ...
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1answer
1k views

What is the force between two charged objects when the space between them is partially filled by a dielectric medium?

I am given two charged particles of same charge at a distance of $r$. They initially apply force $F$. Now an infinite dielectric (of dielectric constant $4$) of width $\frac{r}{2}$ is introduced ...
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3answers
1k views

Does there exist a single plate capacitor(conductor)?

Does there exist a single plate capacitor(conductor)? if yes How will you define the capacitance and potential(difference) of such conductor?
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0answers
99 views

Non-parallel plate capacitor's capacitance [closed]

So far, I fully understood how to find the capacitance of a parallel plate capacitor. However, for the case of non-parallel plate one, how one could solve that kind of problem knowing that one plate ...
3
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4answers
3k views

Is a capacitor in an open circuit charged?

Say I have a circuit consisting of a battery, a wire, an open switch, and a capacitor. The circuit is open since the switch is open. My book says that the capacitor will only be charged when the ...
35
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7answers
7k views

Why doesn't an electron ever hit (and stick on) a proton?

Imagine there is a proton confined in a box and we put an electron at 10 cm distance: It gets an acceleration of thousands of meters/second^2 along a straight line joining the two CM's. One would ...
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0answers
36 views

Why is there a potential well near a hydrogen nucleus?

A hydrogen nucleus consists of a proton and the electric potential is given by the formula KQ/r where Q is +1.6×10^-19. So plotting a function of electric potential with distance r should give a ...
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1answer
41 views

No change in voltage in a capacitor

While trying to solve this question: Photo copy of the question and answer: Question:On charging a parallel plate capacitor to potential V the spacing between the plates is halved and a dielectric ...
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2answers
111 views

How much is a Coulomb, really?

I've heard it said in my physics class that a Coulomb "is a lot of charge". And I believe it; most of the problems I've done in the class so far involve charges on the order of micro-Coulombs (or, ...
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1answer
231 views

Electric Field within the cavity of a conducting sphere?

So the hypothetical situation that I am confused about is below: The situation consists of a point charge, +q, contained within the cavity of a spherical conductor of neutral charge. I understand ...
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1answer
21 views

Gauss Law - charges outside the gaussian surface

I have just learned Gauss Law and this question is bothering me: Suppose a cubic gaussian surface and a charge next to its right side (image below). According to Gauss Law, the electric flux over ...
2
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1answer
411 views

What is Gauss's Law in two dimensions?

I am trying to figure out how the equation for the field if a Gaussian surface was applied to a 2D plane. I did see another question already asked on the subject, but I didn't get a particular ...
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0answers
13 views

Method of image charges (hemisphere on metal) (2) [duplicate]

This is a continuation from Method of image charges (semisphere on a metal) . nbubis helped me a great deal concerning this problem and in this post I want to address my problem with the computation ...
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0answers
20 views

Method of image charges (semisphere on a metal) (2)

This is a continuation from Method of image charges (semisphere on a metal) . nbubis helped me a great deal concerning this problem and in this post I want to address my problem with the computation ...
0
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2answers
93 views

A capacitor with a conductor between the plates [closed]

Consider a parallel plate capacitor of area $A$ with a distance between the plates $d$, disconnected from the battery. I wonder, how would the capacitance of the system change if we placed a conductor ...
3
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1answer
96 views

Method of image charges (semisphere on a metal)

I'm currently trying to study ahead for the upcoming semester since I'm on break and I'm stuck on the method of image charges. I've tried watching some youtube videos on that topic and I thought I ...
0
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2answers
433 views

Graph for Coulomb force vs $1/r^2$

We know that when there is a relation like x inversely proportional to y^2, the graph would be like this: But in this question"Plot a graph showing variation of Coulomb force(F) versus $1/r^2$, ...
5
votes
2answers
2k views

Perpetual motion machine [duplicate]

I'm having trouble understanding why this machine doesn't work. Part of a ring, half of which is uniformly charged, is located between two oppositely charged plates, attracting to the negative one and ...
0
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1answer
15 views

Electric charge due to a point

In my book its written,"Electric field due to a point charge is inversely proportional to 1/r square....This means that at all points on the spherical surface drawn around the point charge, the ...
0
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1answer
24 views

Electric charges and fields

After solving a few questions i have observed two things...Are they true?: When two identical metallic spheres, one uncharged and one charged with lets say +4Q are brought close to each other then ...
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1answer
47 views

Doubt in derivation of electric field at axial snd equatorial point

Firstly, in derivation of electric field at an axial point due to a dipole we have to determine the Electric field at a point P on the axial. So there are two electric fields acting on this Point P, ...
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3answers
32 views

How does a conductor shield the outside from its inside

If I have a charge of +q placed arbitrarily within the spherical conducting shell, by Gauss' law, the E field produced will be created outside the shell, as if the charge were placed at the center. If ...
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0answers
78 views

Electric field at centre of two different hemispheres

I have a sphere separated into two hemispheres which are insulated from each other the bottom half is earthed and the top half has potential $V$. Radius=$a$. I am trying to find the Electric ...