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.

learn more… | top users | synonyms

0
votes
0answers
18 views

Storing energy in cylindrical capacitor [on hold]

Calculate the capacitance per unit length of two coaxial cylinders, the outer one with radius $b$ and charge $Q$ and the inner one with radius $a$ and charge $-Q$. I found that the the electric field ...
1
vote
0answers
30 views

Laplace's equation with spherical, cylindrical, and planar symmetry [on hold]

Find the general solution to Laplace's equation for spherical symmetry (everything can only depend on $r$, the radius), cylindrical symmetry (everything can only depend on $s$, the radius), and ...
1
vote
0answers
28 views

How does a battery work?

How does the positive terminal of the battery attract electrons? Does the electric field emitted by the positive terminal attract the electrons?
1
vote
1answer
49 views

Electron electric field

As we know the fundamental unit of charge in our universe at the time of electrodynamics was an electron, and in any frame of reference, its radius is a finite number and assuming uniform charge ...
2
votes
2answers
27 views

Relationship between surface density and volume density

Often in an E&M problem, I'm having to "chop" an extended object into an infinite sum of smaller extended objects which I know more about to find a potential or electric field or whatever. The ...
0
votes
0answers
12 views

Finding the contained charge in a box, given the $E$-field [on hold]

I'm not sure whether my approach is correct for this problem, it's been a while since I've touched E&M. I thought it best to check, as I'm not sure whether $0$ is the proper answer. I've got a ...
0
votes
0answers
7 views

How does one determine the breakdown voltage of a solid-in-liquid suspension?

So I'm doing a project in which we are supposed to collect micro-scale conducting metal particles from a suspension of it in water (which is deionized). Suppose that I am charging the particles ...
0
votes
1answer
27 views

Gauss's Law :Electric field due to uniformly charged sphere

While determining the electric field due to a uniformly charged conducting or non-conducting sphere,does the sphere is considered hollow or it is considered solid? Can anyone really state , what is ...
3
votes
1answer
51 views

What is the minimum distance between two opposite point charges

In an overly simplistic model if I have a single negative charge, and a single positive charge they will be attracted. I expect they will fly together. Click. Good luck getting them apart. The ...
2
votes
2answers
66 views

Charge outside Gaussian Surface doesn't contribute to Flux?

I roughly understand the explanation for this: any electric field line that enters the surface, must leave it, since field lines can't terminate abruptly in space. My question is, what if you have a ...
0
votes
2answers
37 views

Net Electrostatic Field inside a Conductor is $\vec{0}$

I've heard an explanation for this, and my professor wasn't really able to clarify my questions, so I was hoping someone could help: Suppose there is an electrostatic field $\vec{E_{net}}\ne\vec{0}$, ...
0
votes
0answers
7 views

Would the charges on a superconductor near an another charged conductor move and produce magnetic field?

When there is a charged conducting object near an another charged conducting object the charges on these objects accumulate to the sides where the closest points between these objects are. However, ...
1
vote
1answer
13 views

Electrohydrodynamics: How will electric potential develop in a fluid when potential is applied from ends

Lets say, I have a fluid in a rectangular enclosure (2D). I apply electric potential $U=U_1$ at left boundary and $U_2$ at right boundary. In the lower and upper boundaries, the potential varies ...
0
votes
1answer
30 views

Gauss's Law :To find the Electric Field for a Non-Conducting Sphere

While determining the electric field in a Non-Conducting Sphere using Gauss's law,why the positive charges are considered inside the surface,but in determining the electric field in a conducting ...
0
votes
1answer
25 views

clear picture about charge and flux

What is the difference between charge and electric flux?? According to my knowledge electric flux is nothing but charge enclosed by the closed surface.
1
vote
1answer
59 views

Is it necessary for EM fields to be dependent & co-exist in static conditions?

I was having a discussion today with one my colleagues in the lab about the independence and co-existence of EM fields.$$$$ My argument: In time-varying fields: EM fields are necessary dependent, ...
0
votes
0answers
47 views

Nuclear fission difference in energy calculation?

If you have a uranium atom of radius $10^{-14}m$ that undergoes fission into two fragments each with 46 protons and radius $8\times10^{-15}m$. There are two ways you can calculate the electrostatic ...
0
votes
0answers
36 views

Charge distribution over a finite plate

Let's say we have a tube(simply a cylinder with no top or bottom) with charge $q_1$, radius $r_1$ and length $l_1$ made out of insulating material. There is also a finite conducting plate with sides' ...
1
vote
1answer
27 views

Distribution of energy in an electric and magnetic field

Are the energy of the electric field and the energy of the magnetic field concentrated on their sources OR are they scattered in the environment where the fields arent zero? What is the formula that ...
0
votes
2answers
35 views

Find net force on a mass centered between four other masses

I'm not going to post the full question, I just want a general idea of how I should go about solving this type of problem. There is a square with 4 charged masses on each of the corners, in the ...
0
votes
0answers
36 views

Capacitance changes by a factor of 3 or 9?

This is an example problem with solution in a book I am reading on electrostatics. "We have two square parallel plate capacitors with length $a$ and separation $d$ with $d<<a$. If we triple ...
-1
votes
1answer
32 views

Electric Field of a sphere

Is there a point in space where the electric field is half of the electric field on the surface of the sphere? I just got curious if it would be possible.
0
votes
3answers
47 views

How do we conclude that polarized dielectric in electric field reduces overall field?

If we have a dielectric inside an electric field, the dipoles in the dielectric will align in the following direction due to the torque on them by the external field. The conclusion then is that ...
1
vote
2answers
48 views

protons and electrons

I am a novice in physics and a few things are not clear to me in electromagnetism: Consider the experiment of giving a piece of metal positive charge (which I assume consists of protons), by keeping ...
0
votes
1answer
10 views

How is electric field strength related to potential difference?

I was looking at the derivation of drift velocity of free electrons in a conductor in terms of relaxation time of electrons. Here a metallic conductor XY of length $\ell$ is considered and having ...
1
vote
1answer
33 views

Is the charge of an ion evenly distributed?

This question relates to: Gauss' law and ions? Is the charge distribution in an ion spherically symmetric due to quantum mechanical effects or do we assume it when using Gauss's law, as in the ...
0
votes
1answer
23 views

Gauss' law and ions?

My text book says that with we have a singly ionized sodium atom net charge +e and if we choose a spherical surface centered on the ion and large enough to contain it all we do not need to know the ...
1
vote
2answers
34 views

Why can I blow up other potentials at the origin but not the one inside a dielectric sphere in an electric field?

While solving the electrostatic field for a dielectric in an electric field, we take the potential at origin to not blow and thus, we eliminate the inverse powers of r in the expression for general ...
0
votes
1answer
20 views

Electric force between charges in two different media

As far as I know, Coulomb's law of electrostatic force is applicable on two different charges situated in same medium. But if two individual charges are in different media (say one charge on a iron ...
0
votes
0answers
26 views

Maximum voltage on metal sphere? [duplicate]

What is the maximum voltage that can be put on a metal sphere before electrons fly off it or the metal itself explodes due to electrostatic forces?
0
votes
1answer
37 views

Coulombs law: calculate force exerted on one charge by the other two [closed]

The drawing shows three point charges fixed in place. The charge at the coordinate origin has a value of q1 = +8.00 μC; the other two charges have identical magnitudes, but opposite signs: q2 = ...
0
votes
1answer
32 views

Electrostatics Equilibrium problem [closed]

What should be the value of Q? I am doing the basics of coulomb's law,can anyone explain this to me?
0
votes
2answers
65 views

How can I split a resultant force into its $x$ and $y$ components?

Point charge 3.5μC is located at x = 0, y = 0.30 m, point charge -3.5μC is located at x = 0 y = -0.30 m. What are (a)the magnitude and (b)direction of the total electric force that these charges ...
1
vote
3answers
87 views

Coulomb's Law- Why the Coulomb's law is valid only for point and static charges?

Why the coulomb's law is valid only for point and static charges? Is there is any definite reason?
0
votes
2answers
45 views

Electric Field and Calculus: What is the physical significance of infinitesimal $dA$ in the equation of Gauss's Theorem?

In many equations we see infinitesimals $dA$, $dS$, $dx$ and so on. What is is the physical significance of these? Someone told me it signifies a small entity. For example,in case of $dA$ it signifies ...
3
votes
2answers
62 views

Finding the direction of the magnetic force acting on a conducting wire

I have a problem in finding the direction of the force when a conducting wire is placed in a magnetic field. If I use Fleming's Right Hand rule I get a circular magnetic field, so what will be ...
0
votes
1answer
40 views

How to distribute static charges evenly on a finite plate?

There are several ways to make charges on an object evenly distributed. For example, if the surface of the object is infinite or the object is a sphere. There is one more way which I am not sure if it ...
0
votes
1answer
46 views

Can someone show me how Green's function would apply for this simple case?

I'm reading up on some stuff on basic electrostatic here: http://hyperphysics.phy-astr.gsu.edu/hbase/electric/laplace.html Can someone use Green's function to show me the form of $V$? Update: I ...
0
votes
2answers
30 views

Inductor Charging and Discharging

Why does the inductor discharges in the same path ( same direction of current ) as that of its charging unlike a capacitor which discharges in the direction opposite to its charging(current direction ...
1
vote
0answers
32 views

Contradictory boundary conditions in electrostatics problem?

Consider the following problem: A conducting cube of side $a$ is grounded. Inside there's a horizontal (i.e., perependicular to the $z$ axis) sheet with uniform surface charge density $\sigma$. The ...
1
vote
1answer
35 views

Potential due to charge over infinite grounded plane conductor using the method of images

I am reading section 3.2.1 of Griffiths 3ed which explains how to calculate potential using first uniqueness theorem. Griffiths/3.2.1 Griffiths/First Uniqeness theorem (Its corollary actually) ...
1
vote
2answers
32 views

Why is Lightning referred to as High frequency source?

Lightning strike is categorized as DC because of its electrostatic nature. The negative flash/stroke is found to have 200KA of current with a voltage close to 300KV (cloud to ground). But why is it ...
3
votes
1answer
82 views

Why would a rotating charged sphere not have time varying electric field?

I have seen Gauss Law being used for a uniformly charged hollow sphere rotating with $\omega$. How is that valid to use Gauss law since it is an electrostatic law and if it is valid, why do we get a ...
1
vote
1answer
27 views

How to make charges of a charged conductor evenly distributed over the surface of the object?

Is there a way to make the charges of a charged conductor evenly distributed over the surface? I know the charges of a charged insulator are evenly distributed but I want to know that if there is a ...
2
votes
2answers
31 views

Do charges flow from strong insulator to weak insulator?

Do static charge in a strong insulator flow to a weaker insulator when both stay in contact with each other? For example, when an insulator weaker than air placed in a medium of air, would the static ...
3
votes
4answers
234 views

How can I calculate the force that is applied on a tube by another tube?

Let's say there is two tubes(cylinders with no tops or bottoms) with charges $q_1$ and $q_2$, radii $b_1$ and $b_2$, lengths $l_1$ and $l_2$. These tubes are located along the axis of each other's ...
1
vote
1answer
35 views

How to find whether the electric field between capacitor plates is above or below the electrical breakdown limit of the insulator between the plates?

Let's say the two plates of a capacitor have charges $q_1$ and $q_2$. The separation between these plates is $d$. I know that I can calculate the electric field by dividing the voltage that is applied ...
1
vote
1answer
48 views

image method to calculate the surface charge density on a conducting plate

There is a charge q at a perpendicular distance z = d from an infinite conducting plate z=0. We use the image method and place -q on the other side of the plate and calculate the field. This field ...
3
votes
2answers
89 views

Electric flux through nonspherical surphace

Here's an explanation from a book that I read: Now, I have a few problems with this explanation as well as with the "cone method". I guess that all my problems boil down to the concept of ...
2
votes
2answers
54 views

How much voltage should be applied to an object to create a certain amount of charge?

I am curious as to how much voltage should be applied to create a specific charge. Is there a formula to calculate it, and what are the parameters that can affect the relation between voltage and ...