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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What is the cause of the time-varying electric and magnetic near-fields around a wire with a 60Hz AC current?

I know that it's the accelerating electrons in an AC current that are the cause of far field effects. But, what about the reactive near field close to a wire that has a 60Hz AC current? What is the ...
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What happens to half of the energy in a circuit with a capacitor?

For a simple circuit with a battery supplying a voltage V to a capacitor, let us assume that the charge on the capacitor is Q. Now, the work done by the battery or the energy supplied is given by the ...
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28 views

Calculating rise in water surface due to a charged capacitor

Two metal plates separated by a distance d & initially charged with charge +Q & -Q are kept so that it just touches the surface of a very large water tank as shown in figure a. Thus water ...
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30 views

What does a hexadecapole look like

Two dipoles can form a quadrupole, two quadropoles an octopole. The textbook by Griffith then says ' and so on'. So how would a hexadecapole really look like? My impression was that the construction ...
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21 views

Origin of internuclear forces

I just recently read about the existence of internuclear forces as the reason for the nucleus to remain 'stable' as in it doesn't separate out into protons and neutrons even though there is electronic ...
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Application of Coulomb's Law

I've just finished reading a section in a book on Coulomb's Law. I'm trying to practice the math a bit and came up with the following: Suppose you have two charges, -5uC ($q_1$) and 7nC ($q_2$). ...
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1answer
33 views

Can I get help with measuring particle charge using oscilloscope?

How can one measure particle charge using oscilloscope and op amp integrator circuit along with a capacitor and faraday cup. I am unable to figure out how to approach. I have the circuit ready but ...
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1answer
32 views

Infinite, straight, current-carrying wire uniformly charged to a negative electrostatic potential

I am working on a problem that states the following: Imagine an infinite straight wire carrying a current $I$ and uniformly charged to a negative electrostatic potential $\phi$ I know here ...
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43 views

Capacitance of a single charged plate?

Lets say we have a single plate that has a charge of +Q on it. A plate with charge -Q is infinite distance away. Will the plate with +Q have a capacitance associated with it? Why or why not? I was ...
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51 views

Does the potential of two spheres become equal when we connect them?

I was reading a chapter on capacitors where it was asked whether given two spheres, each carrying a charge $q$ and of radius $r$ and $2r$, will charge flow between them? I assume the answer should ...
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32 views

Five charges on a pentagon [closed]

If we keep five identical point charges at the five corners of a regular pentagon. What will be the electric field at the centre. I think it would be zero due to symmetry.. Please correct me if I'm ...
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174 views

How to approximate trajectories and movement of two oppositely charged particles?

Imagine a single, stationary charged atomic ion, say a Lithium anion or cation (Li+ or Li-). Now imagine another a single free, oppositely charged particle--perhaps an electron or Hydrogen ion ...
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54 views

The image current due to moving charges and a current carrying thin wire

Suppose we have a plane conductor and positive charged particles of mass m are moving parallel to the plane conductor at a distance d. The trajectory can be assumed to be straight. An image current ...
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1answer
34 views

Would a non-conducting body ever acquire a uniform static charge throughout it's volume?

I'm studying electromagnetism and optics in first year and solving a lot of problems involving conveniently symmetrical conducting and non-conducting bodies having various uniformly distributed ...
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2answers
78 views

Are spherical coordinates distances or angles?

I've become confused about spherical coordinates when dealing with electric fields. The way I always understood spherical coordinates is something like the below picture. To define a vector, you give ...
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1answer
22 views

Change in Potential energy moving toward line of charge

I'm analyzing the energy involved with charges moving in an electric field and I'm getting caught up here and I must be missing something. So given that an infinitely long line of charge produces a ...
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1answer
24 views

Total potential energy for two charged particles

I'm trying to formulate a Lagrangian equation for a system of two charged particles. They have respective masses $m_1$ and $m_2$, and respective position vectors $\vec{x_1}(t)$ and $\vec{x_2}(t)$. ...
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1answer
37 views

Constant charge density and magnetic field

Suppose we have an arbitrary number of point charges in a vacuum, described by a constant charge density $\rho$. Can they be the sources of a magnetic field $\mathbf{B}$? My intuition is that they ...
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40 views

The approximation of the potential field of a half wave dipole antenna

I'm currently deriving an approximation of the potential field of an dipole antenna in the far-field in two dimensions, and I have some troubles. Since using two methods give two different answers. ...
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1answer
63 views

Gauss's law and charge on surface

Consider a cone (not necessarily right cone), with a charge $q$ at its apex. Fix its base, and let the vertex be movable. Now suppose we intend to find the flux through the base. Since the flux ...
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1answer
20 views

Electric Flux through metal plate by uniformly charged wire

Suppose a long uniformly charged wire is placed parallel to a thin uniform metal plate of length l and width w.Distance is r.Then how to calculate the electric flux through the plate if the charge ...
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1answer
29 views

Can a proton be trapped by eight other protons?

Q: Eight protons are permanently fixed on the corners of a cube. There's a ninth proton floating at the centre of the cube. Is there an escape for the proton or is it trapped? Justify with a ...
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1answer
44 views

Are $Q1$ and $Q2$ attracted or repelled to the sphere shown in the figure below? [closed]

Can you tell from the image below if Q1 and Q2 are attracted or repelled. Will Q2 only be attracted to the sphere if Q2 is enough bigger than Q1? Will the positive charge inside the shell attract ...
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1answer
45 views

Understanding electric field and potential inside an half-connected wire

Let's say we have a 9 V battery and a wire as shown in the image below: Let's assume H is the reference for measuring potential. I know the potential in F is 9 V, and I know the electric field in F ...
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1answer
42 views

Why did the electric potential energy fall in this situation?

Suppose you have two capacitors configured as shown in the image below. One of them has charge $q$ and the other one is uncharged. Then, you close the switch, allowing charges to flow. After ...
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47 views

Why do electric field lines point in the direction of decreasing electric potential?

Why do electric field lines point in the direction of decreasing electric potential? I came across this sentence in my school book but am trying to understand this ever since. I know that dV=-E.dr ...
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70 views

What is the electric field inside a hollow sphere?

If you have a conducting hollow sphere with a uniform charge on its surface, then will the electric field at every point inside the shell be 0. The reason the electric field is 0 at the center is ...
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1answer
80 views

Deriving Coulomb's law from quantum electrodynamics [duplicate]

Is it possible to derive the Coulomb's law using the principles of quantum electrodynamics? How?
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48 views

A charge $Q$ is placed at a distance $a/2$ above the center of a horizontal square surface of edge $a$ [closed]

A charge $Q$ is placed at $a$ distance $a/2$ above the center of a horizontal square surface of edge $a$, while a second charge $Q$ is placed below one of the vertices of square. Find the flux of ...
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3answers
112 views

Can two electrons attract each other?

Due to electrostatic repulsion the two electrons will repel each other as they both possess similar charges, lets leave gravitational attractive force out of the picture my question is can there be ...
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21 views

Density of polarisation charge is zero always for linear isotropic homogeneous dielectrics?

It seems to me that the volumetric density of polarisation charge in a linear homogeneous isotropic dielectric in an external field is always zero, but I find this rather surprising. Consider such ...
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How can we prove that electric field originate from and terminate on charge using Gauss Law?

We already know that electric field originate and terminate on charge only and they doesn't make any closed path. But is it possible to prove this statement using Gauss Law ? If yes then how ?
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49 views

Current Density Boundary Conditions and its Implications

According to Ohm's Law, one can say $ \overline{J} =\sigma \overline{E} $ if the field is in a conductor, and $ \overline{J} =0 $ if it's in empty space. Now if we take the surface of a conductor and ...
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3answers
55 views

Parallel-plate capacitor working voltage $V={Qd\over{\epsilon_0 A}}$ relationship with plates' distance

I don't understand why the working voltage of a capacitor increases with the plates' distance. Suppose we have 2 capacitors in series where $C_1=12,0\mu F$ and $C_2=4,0\mu F$. The voltage over both ...
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1answer
28 views

Repel air by electrostatic charge

It is known that an electrostatically charged object can repel or attract a flow of water. Can this also apply to an air flow? And if so, would it happen only due to the humidity via water molecules, ...
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1answer
36 views

Is it possible for two polarizable bodies to induce dipoles in each other in the absence of an external electric field?

If there exist two initially neutral bodies (say atoms) some distance apart, with no external electric field applied, can they induce dipoles within each other?
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3answers
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Does the equation CV = q break down when V is small or a wire is very long?

I'm trying to understand how the equation $CV=q$ relating the voltage difference and charge stored on a charged capacitor breaks down under extreme circumstances. In most problem statements that I'm ...
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2answers
64 views

Proof that work is the same whaever the path of approach for two charges

I have a quick question on a figure that outlines a proof. There is a stationary charge $q_1$ and is kept fixed. $q_2$ is moved to the same position along two different paths at a fixed distance ...
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1answer
47 views

What is the distribution of charge on two conducting spheres?

There are two conducting spheres of charges $Q_1$ and $Q_2$ and respective radii of $r_1$ and $r_2$ with center-to-center separation of $L$. Can the distribution of charge on each of the conducting ...
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1answer
28 views

single conducting plane and parallel conducting plane with opposite charge all have different Electric field but same Electric Flux?

Considering the electric field $\vec{E}$ created by an infinite conducting plane $M_1$ having surface charge density $\rho_s$ locate at xy plane at $z = 0$ with $\hat{a}_z$ as unit vector ...
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1answer
99 views

Real life physics problem: Why is my desktop computer affected by my plasma ball?

Note: this is strictly a physics question, not meant to be an advertisement I was running my desktop with a plasma ball on the side. The desktop has a touch screen enabled. I started to notice that ...
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2answers
388 views

Why electric field inside charged conductor is zero in the electrostatic case

I am trying to understand the idea (or the fact) that most books introduce which is about the electric field inside a charged solid conductor Books tell that the field has to be zero everywhere ...
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1answer
22 views

electric field in hollow conductor

when we have a hollow conductor and we charge it then the quantity of charges and electric on and in inner surface of conductor material is zero and this is okay .But is the electric field also zero ...
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1answer
35 views

Electric field and Gauss law

If we take a Gauss surface S to calculate the electric field using Gauss law:$\int\epsilon\vec{E}.\vec{dS}=\sum(Q's\ inside\ S\ +$ $Q's\ on\ S\over2 $ $)$ then this field calculated $E$ is for ...
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1answer
29 views

Confused about voltage due to a point charge

If we have a point charge q then on any point around q we have electric field done by q on this point, and there exist voltage(potenial) of this point due to q which is work done by q to move +1c from ...
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1answer
51 views

Potential and Electric field

I'm trying to find the electric field from the potential and vise-versa but I'm having trouble I know the electric field of a ring with radius a and charge Q to be $$E=\frac{Qx}{4\pi ...
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1answer
30 views

why isn't the net force considered while calculating potential due to a system of charges?

The textbook I'm reading defines potential at a point as work done per unit charge by an external agent to move the test charge from the reference point to the point under consideration (without ...
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Using Gauss's law (differential form) on an infinite line of charge

I just read about Gauss's law in differential form and how to compute divergence. I worked out the $1/r^2$ field and got zero as expected! I was very happy. Then I thought the infinite line of charge, ...
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30 views

How do i prevent static electricity on my trampoline? [duplicate]

Every time i am on my trampoline, i get a nasty static shock when i get down. I have no idea how this is caused. How do i prevent this? My trampoline is a 8ft trampoline with a net surrounding it.
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1answer
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Equipotential inside a conductor ring, but how do I determine the value?

I was mapping the potential lines of 2 cylindrical electrodes - one at 0 V, the other at 5 V. I have a metallic ring midway between the 2 electrodes. I know that the electric field inside the ring is ...