A fundamental property of matter which causes it to experience electromagnetic forces.

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76 views

How can charge be squared?

In many Wikipedia articles I have come across it refers to a Coulomb squared. What does this mean intuitively? i.e. http://en.wikipedia.org/wiki/Farad (this was the most recent place I came across ...
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124 views

What does “charge” actually mean? [duplicate]

I know that a charged particle is defined as a particle that experiences a force in an electric field, as explained in this post: What does a subatomic charge actually mean? However, I still don't ...
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165 views

In which experiments the charge to mass ratio of proton was determined?

Are there experiments where the charge to mass ratio for protons have been determined in the same way as in Thompson’s experiments (where he determined the charge to mass ratio of electron) but with ...
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50 views

The point of charge neutrality in the Hydrogen Atom

If we treat the Hydrogen Atom like the Bohr model then we have a proton in the center with an electron orbiting at some radius (the Bohr radius). In this picture you can imagine the electric field ...
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88 views

Other values of mass of the electron and the charge of the electron?

Are there whatever experimental data other than Millikan Oil Droplet experiments data and Stoney calculations from electrolysis low, or some experimental indications pointed on the possibility that ...
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27 views

If iI have a capacitor connected to a battery can the negative charge be sent to an insulated object

If I have a capacitor permanently connected to a battery, that is lets say setting in a plastic bowl, and then run a wire from the negative of the battery to a non grounded object, say a metal can ...
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54 views

The force applied by two charges on each other when there is another charge nearby them

QUESTION 1 Let me give two simple scene of charged particles to make you understand my question. There is a fixed positive charged particle in the center. Scenerio 1 : A fixed negative charged ...
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41 views

Where does the net charge on a hemisphere appear to act from?

I was wondering if, like centre of mass, there is anything called "centre of charge".
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36 views

Average distance between electrons on a parallel plate capacitor

I came across this question in an old exam paper and I am interested in the way it was marked. The 'correct' answer doesn't seem to be as correct as it could be. Calculate the average distance ...
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46 views

A 100 000 km wire in contact with a positively charged sphere

A long copper wire (see the picture), placed somewhere in the outer-space, having the length $L=100000 km$ and the cross section $S=1 cm^2$, comes in contact at one of its ends ($x = 0$) with a $+Q$ ...
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46 views

Capacitance question

A capacitors capacitance, C is equal to Q/V right? If Q was somehow cut in half, would the potential difference also be cut in half, since V is directly proportional to Q? And if so, Its C would be ...
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29 views

Dipole moment of a displaced charge distribution [duplicate]

This one is part b) of the problem I asked a day ago. Special thanks to MarkMitchison and sbp on the first part. I finally got it. (How can I prove that the dipole moment is zero?). Alright, back to ...
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121 views

Can the surface charge density be negative somewhere on the inner surface of a spherical conductor shell?

A positive charge $q$ is located off-centre inside a conducting spherical shell. We know that the total charge on the inner surface of the shell is $-q$. Is the surface charge density negative over ...
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16 views

Find Electric Field at certain radii for a sphere

If radius of non-conducting sphere is R=4cm, find Electric field at r1=3 cm (for inner Gaussian surface) and r2=6cm(for outer Gaussian surface) Volume charge density is given as: ρ = c r^2 where c ...
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24 views

Explanation to the flow of charge

I came across a really cool Cymatics video: There is one part in the video which is unclear to me. Please refer to the snapshot below taken at 05:15. I see the equipment being close to a Van de ...
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1answer
112 views

Radially symmetric charge distribution (dipole moment) [closed]

a) There's a radially symmetric charge density $\rho(r)$ centered around the origin. Determine the dipolemoment of that charge density. b) Let $\rho(r)$ be an arbitrary charge density now. ...
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2answers
97 views

Charges on capacitor after full charge by battery

When the charging is finished what will be the charge on an ideal parallel plate capacitor ? To be specific what are the charges on different faces of the 2 plates ? All the books say, after 100% ...
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45 views

Dipole Moment (spherical/arbitrary charge density) [duplicate]

I'm new here. I got to this website while searching for links to fill my gaps on some topics. I have found some amazing posts for many different topics. Just amazing. Anyway, I'm currently dealing ...
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56 views

Do virtual photons give particle charges?

I think the electric field is due to the exchange of virtual photons constantly emitted by the point charged particle such as an electron, does this apply to proton which is consisted of quarks? does ...
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1answer
50 views

Could someone simply explain how a railgun works?

Could someone simply explain how a railgun works? What could possibly accelerate an object that fast in such a short distance? I've heard it has to do with current between two rails, but I simply do ...
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1answer
104 views

How strong a magnetic field would be needed to deflect cosmic rays?

How strong a magnetic field would be needed to deflect cosmic rays? For example, lets imagine we wanted to protect the occupants of the International Space Station from cosmic rays. I assume we would ...
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1answer
128 views

Does a Tesla coil work in space?

If I took a Tesla coil into space, and then turned it on near, but not touching metal objects- would charge jump to the metal objects? It's my understanding I wouldn't see a flash, since the lightning ...
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1answer
44 views

Time derivative of Noether charge

I understand that the Noether charge can be written as $$ Q= \int d^3 x J^0$$ and the time derivative of the Noether charge is zero $$ \dot Q=0 $$ but how would you explicitly calculate it?
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78 views

Is antimatter attracted to matter by its opposite electric charge?

As it is said by many physicists that antimatter is just opposite of matter; it has opposite charge of matter, then is there is any possibility that antimatter is attracted to matter? For example - ...
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50 views

What is the “practical purpose” of Gaussian surfaces?

Without having the concept of a Gaussian surface, we know that charges induce fields in proportion to quantity. Now to take a common example, when describing flux through a (physical) surface it is ...
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87 views

Is this charge density function, from a problem in Griffiths' book, a physically valid density?

This is from the book on electrodynamics by Griffiths: A sphere of radius $R$, centered at the origin, carries charge density $$\rho(r,\theta)= k(R/r^2)(R-2r)\sin(\theta)$$ where $k$ is ...
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63 views

Validity of law of charge conservation

Charging by induction and earthing gives an object a net charge but why does the law of charge conservation still hold in this case?
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359 views

Derivation of capacitive reactance

Let $Q(t)$ be the charge stored in a capacitor $C$ in $t$ time for alternating current. Now, $$\displaystyle Q(t)=Q(0)+\int_{0}^{t}I(t)dt\\=Q(0)+\int_{0}^{t}I_oe^{j\omega ...
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2answers
127 views

Why is the charge of a proton positive? [duplicate]

Is there a reason that a proton has a positive charge while an electron has a negative charge? Are these just names that were given to the charges or was there a reason for making a proton have a ...
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67 views

signal from uniformly moving charge

As a charge moves, its field changes, and this change can only be propagated outward at the speed of light. Thus the field lines will be curves that keep changing apparent source point and direction. ...
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4answers
97 views

Where is the fallacy in this issue related to electric charge quantization? [closed]

Suppose there are two identical conducting objects; one with 5 units of positive charge and the other is uncharged. Initially these are separated and later these are brought into contact. I guess net ...
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2answers
223 views

Definition of a line charge with Dirac delta function [closed]

Is the following statement correct for a line charge distribution $λ(x)$? $$ρ(\mathbf r)=λ(x)δ(y)δ(z)$$ If yes - what does it say?
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244 views

Why is the potential energy of a dipole in an electric field zero when the dipole points perpendicularly to the field?

I have read that potential energy of a dipole in an electric field is taken to be zero at 90 degree as they say that it is a reference. But there must be some reason behind it?
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28 views

Electric field uniform circle $R$ direction cancel out

I am doing a physics problem involving a uniform circle with a total charge of X, and am attempting to find the electric field on a point charge on the axis of the circle a distance of Z away. I ...
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32 views

Finding Charge given Electric Field

This question came up in a competition, and I didn't know how to solve it. ABCD is a rectangle with width $2d$ and height $d$. At point D, there is a charge with magnitude $q_1$ At point B, there ...
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122 views

diffusion velocity

i understand that diffusion is the movement of particles from high concentration areas to low concentration, but what is the cause of that movement atomically. And especially in the case of charge ...
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2answers
393 views

Maximum limit of charging a capacitor

We say that we can charge a capacitor in proportion to the potential difference we apply across its plates and the maximum potential difference depends on the dielectric strength of the medium. Now ...
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2answers
147 views

Why is charge constant in series connections?

Why does each capacitor in a series connection hold the same charge? I understand that voltages and capacitances across capacitor plate pairs in series vary, but why is it a necessity that charge be ...
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1answer
74 views

Balloon and Static Electrcity

I am learning about charge, but there is one thing I don't understand. In the above picture, I understand that the balloon sticks to the wall because of the attraction between the negative charge ...
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1answer
101 views

What does electrically charged mean?

So I was reading my physics textbook and it said that "Suppose we have two metal spheres, one highly charged and the other electrically neutral." What does it mean by highly charged? Does that mean ...
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1answer
194 views

Method of image charge for cylindrical conductor

I am simply puzzled that only for spherical and planar conducting surfaces the method of images is applied. Is it (really) impossible to find image charge or charge distribution which can simulate the ...
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1answer
183 views

How charges can be at rest if there is a force on it?

Electrostatics deals with forces between charges at rest. But if there is a force on a charge, how can it be at rest? My guess is that charges is being kept at rest by some unspecified forces that ...
2
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1answer
405 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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95 views

Relationship between electric field and distance

I am working on a lab report that asks a conceptual question related to one of the labs we did on electrostatic fields. For the context of my question, here is how the experiment is set up. We have ...
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1answer
64 views

Calculating the rate of electrostatic discharge via current density

After I asked this question, with the help of Floris' comment, I tried to learn more about the concept of current density and tried to calculate the current density in my scenerio which, it seems, is ...
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81 views

Derivation Electric force

I’m a physics of high school (SMAN 3 Bandar Lampung, Lampung, Indonesia 35116). I make the experimental apparatus in static electric field. Instrument arrangement in the image below: The theoretical ...
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1answer
82 views

Deriving the Lienard-Wiechert Potentials

Let $\mathbf{w}(t)$ be the trajectory of a moving charge. Let the observation event be $(\mathbf{r},t)$. The scalar potential is: $\phi = \frac{q}{4\pi\epsilon_0}\int \frac{\delta(\mathbf{r'} - ...
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2answers
114 views

Is Quantum Coulomb still singular?

A single free charge (e.g. electron) $q$ fixed at the coordinate origin has the well-known Coulomb/electric potential $$\phi(\vec r) = \frac q{4\pi\epsilon_0}\frac 1r \tag{A}$$ where $r=|\vec r|$ of ...
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39 views

prototyping a cyclotron , a charging problem

I'd like to model a cyclotron but not with subatomic particles but with a small metallic ball but the problem is i need to charge the metallic ball with certain amount of charge and i must know it to ...
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1answer
272 views

Finding the electric field at a point from half of a uniformly charged rod

The image below is a rod of length that is uniformly charged to total charge at a point along the perpendicular bisector of the rod above distance . I know the formula for finding the electric ...