The charge tag has no wiki summary.
32
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7answers
2k views
Why do we have an elementary charge but no elementary mass?
Why do we have an elementary charge $e$ in physics but no elementary mass? Is an elementary mass ruled out by experiment or is an elementary mass forbidden by some theoretical reason?
11
votes
4answers
2k views
Why is the charge naming convention wrong?
I recently came to know about the Conventional Current vs. Electron Flow issue.
Doing some search I found that the reason for this is that Benjamin Franklin made a mistake when naming positive and ...
10
votes
4answers
2k views
Why do electron and proton have the same but opposite electric charge?
What is the explanation between equality of proton and electron charges (up to a sign)? This is connected to the gauge invariance and renormalization of charge is connected to the renormalization of ...
7
votes
6answers
609 views
What prevents the accumulation of charge in a black hole?
What prevents a static black hole from accumulating more charge than its maximum? Is it just simple Coulomb repulsion?
Is the answer the same for rotating black holes?
Edit
What I understand from ...
7
votes
2answers
1k views
Why do we need Higgs field to re-explain mass, but not charge?
We already had definition of mass based on gravitational interactions since before Higgs. It's similar to charge which is defined based on electromagnetic interactions of particles.
Why did Higgs ...
7
votes
2answers
287 views
why dosen't a charged particle radiate energy in circular motion in a uniform magnetic field?
I have studied in my Physics course that one of the drawbacks of Rutherford's atomic model was that when an electron will revolve around the nucleus, it is undergoing acceleration and so it should ...
7
votes
1answer
844 views
Electric charge in string theory
The mass of an elementary particle in string theory is related with the way the string vibrates. The more frantically a string vibrates the more energy it posses and hence the more massive it is. My ...
6
votes
3answers
339 views
Charging a black hole?
What would happen if we have a black hole and we start shooting at it a single electron at a time, and go on doing it forever? Would the electrons start to bounce off eventually?
5
votes
1answer
544 views
What defines the maximum charge a capacitor can store?
The formula for a capacitor discharging is $Q=Q_0e^{-\frac{t}{RC}}$
Where $Q_0$ is the maximum charge. But what property defines the maximum charge a capacitor can store?
If it depends on ...
5
votes
3answers
243 views
Negative Mass and gravitation
Since Newtonian gravity is analogous to electrostatics shouldn't there be something called negative mass? Also, a moving charge generates electric field, but why doesn't a moving mass generate some ...
5
votes
5answers
447 views
Paradox with Gauss' law when space is uniformly charged everywhere
Consider that space is uniformly charged everywhere, i.e., filled with a uniform charge distribution, $\rho$, everywhere.
By symmetry, the electric field is zero everywhere. (If I take any point in ...
5
votes
2answers
166 views
Is there a momentum for charge?
Since mass and charge behave similarly, so, just like center of mass, I define a point center of charge, that is defined by
$$\vec r_{qm} = \frac {\sum{q_i \vec r_i}} {\sum{q_i}}$$
where $\vec r_i$ ...
5
votes
1answer
200 views
How can I prevent my son building up static on his trampoline?
Whenever my three year old son plays on his trampoline, it doesn't take very long for him to start building up a significant amount of static electricity. His hair stands on end (which is quite ...
4
votes
3answers
238 views
Change in attraction of charged bodies
If I insert a piece of glass between two objects carrying different charges, would they still attract?
If they attract, does the piece of glass affect the force of attraction and is there any formula ...
4
votes
3answers
133 views
How quark electric charge directly have been measured?
How quarks electric charge directly have been measured when quarks never directly observed in isolation? (Due to a phenomenon known as color confinement.)
4
votes
2answers
153 views
Is it possible to charge photons
For example there are anti-particles to every particle we know,
Similary in some sense, is there a possibility that we can charge photons..if not what are the reasons and has there been any attempt ...
4
votes
2answers
496 views
What happens to capacitor’s charge when the plates are moved further apart?
In my physics textbook there is an example of using capacitor switches in computer keyboard:
Pressing the key pushes two capacitor plates closer together, increasing their capacitance. A larger ...
4
votes
2answers
244 views
Sum total distance of electrons on a spherical surface
What is the sum total distance between every possible pair of point charges when there are n point charges on a spherical surface?
All point charges can only and are located on the infinitesimal ...
4
votes
1answer
284 views
Noether theorem and classical proof of electric charge conservation
How to prove conservation of electric charge using Noether's theorem according to classical (non-quantum) mechanics?
I know the proof based on using Klein–Gordon field, but that derivation use ...
4
votes
1answer
54 views
How much negative charge do I accumulate by touching the earth?
The Earth carries a negative electric charge of roughly 500 thousand Coulombs (according to different sources I've seen). If I touch the Earth I should therefore pick up some of this electric charge ...
3
votes
3answers
146 views
How is possible for current to flow so fast when charge flows so slow?
How is possible for current to flow so fast when charge flows so slow?
We know electrons travel very slowly while charge travels at ~the speed of light.
3
votes
2answers
74 views
Regarding the free electrons on the conductor
In a metal, why don’t the free electrons fall to the bottom of the metal due to gravity?
Also, charges in a conductor are supposed to reside on the surface so why don’t the free electrons all go to ...
3
votes
3answers
693 views
What is the maximum surface charge density of aluminum?
I understand that the maximum free charge carrier density for aluminum has been measured using the Hall effect (in the case of electric current). However, I'm not clear how to determine the maximum ...
3
votes
1answer
222 views
What is “charge discreteness”?
I assume it is some kind of quantity. Google only made things more confusing.
I get that it has something to do with circuits.
I also get what a discrete charge is. In fact, I thought charges ...
3
votes
1answer
54 views
Why does the comb attract the pieces of papers if they're neutral?
When we rub our hairs with a comb, and then try to attract small pieces of paper, they're attracted by the comb. The pieces of the paper were not electrified before they were attracted. Then they ...
3
votes
3answers
148 views
Charge Analog of the Higgs Boson?
Since mass can be given to particles via the interaction with the Higgs Field could there be a "Charger Field" that supplies particles with charge? Possibly this would require two different "charger ...
3
votes
1answer
145 views
Origin of electric charge
Baryons have charges that are the result of a polynomial calculation of their building blocks (quarks)'s fractional charges. But what gives these quarks electric charges? What interactions do they ...
3
votes
3answers
311 views
Gravity stronger than electromagnetic force in a black hole?
Well, the question has somewhat been answered before, but there's one part missing, which - I'd think - is in conflict with the physical laws.
The earlier reply says that the gravitational pull even ...
3
votes
1answer
130 views
Charge and the Dirac field
In Zee's quantum field theory in a nutshell, 2nd edition, pg 550 he has
$Q=\int {d^3p \over (2\pi)^3(E_p/m)} \sum_s \{b^\dagger(p,s)b(p,s)-d^\dagger(p,s)d(p,s)\}$
showing clearly that $b$ ...
3
votes
1answer
91 views
Make water droplets charged?
Normally water molecules are electrically neutral.
But I have seen somewhere ideas about electric energy generators mentioning that water droplets might be used in some applications as they are ...
3
votes
1answer
139 views
Why are electric charges allowed to be so light but magnetic monopoles have to be so heavy?
My question is in two parts.
What is the origin of the electric field from an electric charge and why electron can have so small mass? While on the other hand for a magnetic monopole to create a ...
3
votes
1answer
154 views
What do physical properties of materials trigger the capacitive touch screen?
I have watched some youtube videos about capacitive touch screen
http://www.youtube.com/watch?v=ZHzaVzYEZbw
http://www.youtube.com/watch?v=GmCE18RMEeQ
The videos show that a conductor(finger), in ...
3
votes
1answer
369 views
Electric Field due to a charged sphere
Suppose we have a spherical surface with a surface charge density varying as $cos(\theta)$. Apparently one can find the electric field both outside and inside such a spherical surface by superposing ...
3
votes
2answers
269 views
Conservation of Charge and Method of Images
Consider the typical problem, "You have a conducting sphere of charge $Q$ and a point charge q a certain distance away, what is the force on the point charge?". The solution is a simple application of ...
3
votes
1answer
234 views
What's the deepest reason why QCD bound states have integer charge?
What's the deepest reason why QCD bound states have integer electric charge, i.e. equal to an integer times the electron charge?
Given that the quarks have the fractional electric charges they do, ...
3
votes
0answers
62 views
How can I find the position of an image charge when the boundary is parabolic or hyperbolic?
If the position of some charge Q is known, the boundary condition is u=0 on some parabolic surface, and we know the image charge has its electric volume of Q', then how can I determine the position of ...
2
votes
3answers
280 views
Delta Dirac Charge Density question
I have to write an expression for the charge density $\rho(\vec{r})$ of a point charge $q$ at $\vec{r}^{\prime}$, ensuring that the volume integral equals $q$.
The only place any charge exists is at ...
2
votes
2answers
215 views
Electric field of a negative charge
How was it discovered that the electric field of a negative charge points towards the charge itself? Is it true?
(Courtesy of wikipedia)
2
votes
4answers
163 views
How does positive charge spread out in conductors?
I know that when there are excess positive charges in a conductor, for example, a metal sphere, the positive charges will spread out over its surface. However, I am confused about how this excess ...
2
votes
2answers
65 views
Empirical bound on sum of electron and proton charge
Followup to "Why do electron and proton have the same but opposite electric charge?".
It is argued that even a tiny residual charge would result in huge amounts of electricity in bulk matter, ...
2
votes
1answer
70 views
Point charge 4-current derivation
How do I derive that the 4-current of a point charge is
$$j^{\mu}(x)=ec\int_{-\infty}^{+\infty}\dot{z}^{\mu}(s)\delta(x-z(s))ds$$
where $\dot{z}^{\mu}(s)$ is the 4-velocity of the charge and $s$ is ...
2
votes
3answers
127 views
Explanation on the resulting forces of two positive point charges
Why will the resulting force lines of two positive point charges be like this:
I would expect this:
2
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2answers
82 views
Ashcroft Mermin Eq. 17.47ff
In "Solid State Physics" by said authors, Eq. 17.46 is
$$ \rho^{ind}(\textbf{r}) = - e[n_0(\mu + e\phi(\textbf{r})) - n_0(\mu)]$$
and then the authors write
In the present case we assume that ...
2
votes
1answer
53 views
Topological vs. non-topological noetherian charges
What (if any) is the relationship between the conserved (non-topological) noetherian charges and topological charges? Namely, is there any "generalization" of the Noether's first theorem that includes ...
2
votes
3answers
106 views
Is electron velocity at induction higher than in a wire?
When looking to the electrostatic induction on a microscopic level, do the electrons really move with high velocities or they move like when a current passes through the wire (slowly).
2
votes
1answer
79 views
Two capacitors sharing charge
My two capacitors:
I have these two capacitors ($C_1 = 3\mu F, C_2 = 4\mu F$) both initially under 19 volts. Then, I added a dielectric with $k=4$ at $C_1$ and entire ...
2
votes
1answer
68 views
Electrostatic charge leakage
What are the ways electrostatic charged objects leak charge in humid conditions?
Can airborne particles pick up charge by contact, then be repelled hence removing charge? If so would it be a ...
2
votes
2answers
147 views
Energy in electric field
I'm having some trouble understanding a homework question and would appreciate some help.
The question is as follows:
Jenny charges a capacitor with the help of a battery. She then removes
the ...
2
votes
1answer
82 views
Infinite Energy of Point Charges (in the context of classical field theories)
In the context of classical physics,is there any renormalization method to avoid infinite energy of point charges?
2
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3answers
144 views
If photons can be absorbed by electrons, wouldn't that mean light has a charge? [duplicate]
I am a biochemistry and molecular biology major. If photons can be absorbed by electrons, wouldn't that mean light has a charge? Electrons only attract positive charges. Isn't it?
