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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16 views

Electric field calculation and its graph vs x

Electric field along the line passing through two point charges, A point charge $Q_1= +3 \mu C$ is placed at the origin and a point charge $Q_2= -7\mu C $is placed at $x=0.4 m$ on the $x$-axis of a ...
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2answers
27 views

How does friction product heat?

Suppose there are two similar particle-like objects attempting to "bump" against each other to create friction, they are prevented from colliding against one another due to either electrostatic ...
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0answers
28 views

Electric circuit question [on hold]

A 100W bulb is connected in series with a room heater.If now 100W bulb is replaced by a 40W bulb,the heater output will (Decrease) (Increase) (remain same)? And explain why?
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0answers
11 views

Electric Flux through a lamina

I was wondering what the electric flux would be through a square (or any planar lamina for that matter) if I placed a charge at the centre of the square. I think that it will be 0 since none of the ...
0
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1answer
36 views

The influence of electric potential of a planet to a spaceship

How does the electric potential of a planet influence a spaceship? If a distant planet is at very high potential compared to Earth. A spaceship is sent from Earth to land on the planet. Is the mission ...
1
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2answers
44 views

Induction in Electrostatics

While solving some problems on electrostatics, I came across this question : Two balls carrying charges of +3 $\mu C$ and -3$\mu C$ attract each other with a force $F$. If a charge of +3$\mu C$ is ...
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0answers
21 views

Physical intuition for quadrupole source

In his Theory of Vortex Sound M. S. Howe defines sources "mathematically" (i.e. dipole is a source that could be described as a vector and than there is proved that it's equivalent to a two point ...
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0answers
23 views

Voltage between conductors in single phase line [on hold]

I am trying to understand capactiance between conductors in a single phase line, but I am stuck, I am following this ...
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2answers
25 views

How can plants rooted on the ground become charged?

According to a quote on the physics forum "Plants are usually charged negatively and emit weak electric fields." Reference However this seems to contradict the fact that plants are grounded and any ...
1
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0answers
39 views

Calculating the electric charge of two spheres knowing their potential

I have a system of two spheres, the first one is at a potential of $ V_1 = 1 V $ and the second one is at a potential of $ V_2 = 0 V $ The distance between them is $d$ and the radius are respectively ...
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0answers
14 views

Net charge in a conductor

Why does the net charge in a conductor with a cavity becomes zero although we find that the field line from the cavity having a charge +q reaches to the surface of the conductor?
1
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1answer
32 views

Potential of a sphere induced by a charged sphere

I am trying to solve what seems like a simple problem but something is bothering me: Imagine we have a sphere (1) with a charge $Q_1$ and at a distance $d$ we have another sphere (2) which is a ...
0
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1answer
20 views

Why must the belt in a van de Graaff generator be insulating?

If it were conducting then it would not be required to be constantly driven over the pulley; the positive charge gained at the bottom could just flow directly to the large sphere.
0
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0answers
9 views

Electromagnetics [on hold]

the electric potential V(z) between two transmission lines is 6000KV, calculate the electric field the two transmission lines exert on each other,If the electric field is vertically downwards and V1 ...
0
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1answer
39 views

What is the dimension of the solution for Laplace's equation between two cylinders?

Calculate the $\phi$, satisfying $\nabla^2 \phi=0$ between the two cylinders $r=a$, on which $\phi=0$, and $r=b>a$, on which $\phi=V$. I calculate it and found the solution is ...
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3answers
27 views

Lower limit value of electric force [on hold]

What is the lower limit value to the electric force between two charges separated by a fixed distance?
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1answer
29 views

How to calculate Electric Field near a charged conducting surface without Gauss' law?

I have two problems : In every textbook I find the use of Gauss' law in calculation of Electric Field near a charged conducting surface. Can it be calculated without Gauss' law? Suppose while using ...
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votes
1answer
58 views

In Gauss's law, why do we use an infinte long wire or long plane to calculate electric field intensity?

In the NCERT textbook of class 12, in the section on applications of Gauss's law, there are three applications. The first application is to calculate the electric field intensity around an infinitely ...
4
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2answers
56 views

Electric field due to a uniformly charged FINITE rectangular plate

I was teaching kids about how to find electric field using the superposition principle for continuous charge distributions, I thought may be I should derive the formula for electric field due to the ...
0
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0answers
58 views

Understanding Millikan's oil-drop experiment

This is quoted from A.P. French's Newtonian Mechanicsabout Millikan's oil-drop experiment: The droplets randomly produced in a mist of oil vapor are of various sizes. The ones that Millikan found ...
0
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1answer
29 views

How to find the distribution of charge on two spheres connected by a conducting wire?

A solid metal sphere of radius $R$ has charge $+2Q$. A hollow spherical shell of radius $3R$, concentric with the first sphere, has net charge $-Q$. What would be the final distribution of the charge ...
1
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1answer
29 views

Physical meaning of the separation constants in Laplace's Equation for Electrostatics

In Electrostatics, if we consider a region without charges the electrostatic potential $V$ obeys Laplace's Equation $\nabla^2 V = 0$. We can tackle this with separation of variables. In cartesian ...
1
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2answers
61 views

Force when distance between charge is zero

According to coulomb law $$ F = \frac{q_1q_2}{r^2} $$ I want to know what happens to force when $r=0$. If $F \to \infty$ then the charges can't be separated! But if an unlike charge of higher ...
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0answers
22 views

Is there a way to calculate the surface charge density on an infinite plate without using the method of images?

This is the problem: A point charge $q$ is located at a distance $l$ from the infinite conducting plane. Determine the surface charge density induced on the plane, as a function of the distance ...
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1answer
19 views

Change in radius of a charged bubble

I was thinking about what'd happen to the radius of a bubble, if a charge is uniformly distributed over it. At the beginning, I thought that the bubble would expand, for sure, because of the ...
2
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2answers
59 views

Electric potential inside a conductor

I just began studying electrostatics in university, and I didn't understand completely why the electric potential due to a conducting sphere is $$ V(\vec{r})=\begin{cases} ...
1
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1answer
38 views

Question regarding charge and acceleration

From a stationary charge electrostatic fields arise. From a moving charge, magnetostatic fields arise. From an accelerating charge, EM waves arise. So i wonder -- what about a non-constantly ...
2
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1answer
93 views

Physical interpretation of single layer potential in the plane

Let $\Omega\subset\mathbb{R}^2$ be a bounded domain with smooth boundary $\partial\Omega$. The single layer potential with charge density $f$ sitting on $\partial\Omega$ is defined by ...
1
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1answer
143 views

How did Feynman prove that energy cannot be extracted from electric field?

In the Feynman Lectures, vol. II, chapter 4, Feynman discusses electric potential and says: If we carry a charge from point $a \to b$, $$W = -\int_{a}^{b} \mathbf{F} \cdot ds.$$ Now, in general, ...
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1answer
45 views

Does one *feel* the electrostatic force while not resisting it?

Suppose that I put lots of big magnets around me, or say, that I charge myself up to a macroscopic charge. Now, suppose that there's a huge magnet in front of me (or a huge object with opposite ...
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2answers
31 views

Direction of electric field lines and electrostatic force

Direction of electric field and electrostatic force should be same by the equation $$\vec{F} = \frac{k q q_0}{r^2}$$ Electric Field $$\vec{E} = \frac{k q}{r^2}$$ Let us suppose that there is a ...
2
votes
1answer
25 views

Why does the medium affect the Coulomb's constant but not the gravitational constant?

Why does the medium affect the Coulomb's constant but not the gravitational constant? My friend said maybe the particles of the medium affect the electric field. But the net charge in the medium is 0 ...
0
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0answers
17 views

Charge distribution in a heterogenous coin

Basically I am interested in calculating the amount of charge that belongs to two parts of a bimetalic coin. See the picture for an example of how the coin should look like. Suppose the total charge ...
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0answers
20 views

What is the electrostatic force between charges if they separated by a combination of dielectric media? [duplicate]

How does the combination of different medium affect the force? How do we calculate the equivalent dielectric constant? Say, two charges are separated by 100 cm, first 10 cm is a slab of dielectric ...
1
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1answer
37 views

The force on the northern hemisphere

I am reading Griffiths' Introduction to Electrodynamics. On page 364, example 8.2 (4th edition), he calculates the force on the northern hemisphere of a ball with total charge $Q$ spread uniformly. ...
0
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1answer
28 views

Induced electric field

Let's consider a thin cylinder of radius $r$ with a charge in is outer surface. It is made of an isolator. Let the magnetic field be parallel to its axis. If the magnetic field changed by $dB$ in time ...
0
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2answers
63 views

Checking for equilibrium in a square configuration of charges [closed]

Four equal positive charges each of magnitude q are placed at the respective vertices of a square of side length l. A point Q is placed at the centre of the square. Then find the state of equilibrium ...
1
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1answer
13 views

Displacement vector in parallel plate capactor

This ought to be simple, but I'm running into some questions... Let's say we have a parallel plate cap with some linear homogeneous dielectric media between the plates. The plates are distance $a$ ...
1
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1answer
38 views

Electric flux of a point charge in 2D

I am working in two dimensions and have a point charge in the $x$-$y$ plane at the origin. The charge is surrounded by a square walls, $-0.5<x<0.5$; $-0.5<y<0.5$, which are grounded. If I ...
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1answer
61 views

Computational physics using mathematica [closed]

So I was confused about this question on how to exactly begin to answer it. I am a novice in mathematica and I am teaching myself thus I require help in this question. From what I think I should do, ...
1
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1answer
65 views

Potential of a uniformly charged hollow sphere [closed]

If I use Gauss' theorem I find that, for $r\geq R$ $$V(r) = \frac{\sigma R^2}{\epsilon_0 r} = \frac{Q_{sphere}}{4\pi\epsilon_0r}$$ where $\sigma$ is the surface charge density and $R$ the radius of ...
0
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1answer
78 views

Charge present at the centroid of equilateral triangle

Three equal charges +Q each are placed on the vertices of an equilateral triangle. A charge +q is initially placed at the centre of the triangle. If this charge (+q) is slightly displaced towards a ...
1
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2answers
73 views

Obtaining electric field of an uniformly charged sphere surface without using gauss law [closed]

How can i obtain the electric field due to a uniformly charged sphere surface without using gauss law on a point outside the sphere, im stuck not knowing what infinitesimal surface i shall consider so ...
3
votes
2answers
59 views

Will the electrostatic force between two charges change if we place a metal plate between them?

If a thin metal plate is placed between two charges $+q$ and $+q$, will this cause a change in the electrostatic force acting on one charge due to another? What is the concept behind this? What will ...
0
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0answers
21 views

Accurateness of measurement of 1Ampère for the last years, especially depending from the method how to switch on the current?

From Wikipedia: Ampère's force law states that there is an attractive or repulsive force between two parallel wires carrying an electric current. This force is used in the formal definition of the ...
1
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1answer
33 views

How does the magnetic field generated from a rectangular cross-sectional current-carrying conductor differ from a circular cross-sectional conductor?

I can find much information of cylindrical conductors (ie. regular wires), where $B=\frac{\mu_0 i}{2 \pi r}$ and $r$ represents the radius (or distance) from the centre of the conductor, however I ...
1
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2answers
33 views

Electrical breakdown due to a charge

Electrical breakdown occurs due to the fact that the magnitude of electric field of a charged object is above the electrical breakdown limit of the insulator that surrounds the charged object. ...
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2answers
38 views

Why can't electric potential be negative?

As a general concept, potential energy of a configuration is equal to the work done by an external force against an existing conservative force. It is this work done that gets stored in the body as ...
0
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0answers
13 views

Coulombian force when the 2 charges are in different mediums [duplicate]

2 charged particles are kept at a distance r. The mutual force of attraction/repulsion is F. What happens to the force when only one charge is kept in dielectric medium (k) other is in vacuum
1
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1answer
35 views

Potential in uniform fields

First in a book I found that the electric field strength $\mathrm{E}$ of a uniform electric field from a charged plate is equal to $\frac{q}{2\times \epsilon_0 \times S}$ where $q$ is the charge of ...