A fundamental property of matter which causes it to experience electromagnetic forces.
Questions tagged [charge]
3551 questions
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How and why do accelerating charges radiate electromagnetic radiation?
Let's consider it case by case:
Case 1: Charged particle is at rest. It has an electric field around it. No problem. That is its property.
Case 2: Charged particle started moving (it's accelerating). We were told that it starts radiating EM…
claws
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Why do same/opposite electric charges repel/attract each other, respectively?
I know plus pushes another plus away, but why, really, do they do that? On the other hand, molecules of the same type are attracted to each other. I find that weird.
I do know some stuff about four universal forces. But why in general the general…
Muhammad Umer
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How does this baby rattle work?
Here's a gif showing how the balls move when I move the rattle. The circular tube hangs vertically, with the balls on the bottom. There are more images in the bottom.
The balls roll freely inside the tube
The inner diameter of the tube is larger…
Stewie Griffin
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7 answers
Does a charged particle accelerating in a gravitational field radiate?
A charged particle undergoing an acceleration radiates photons.
Let's consider a charge in a freely falling frame of reference.
In such a frame, the local gravitational field is necessarily zero, and the particle does not accelerate or experience…
Sergio
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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 negative charges.
There is even this little comic…
GetFree
- 1,321
77
votes
8 answers
Massless charged particles
Are there any massless (zero invariant mass) particles carrying electric charge?
If not, why not? Do we expect to see any or are they a theoretical impossibility?
Eelvex
- 1,270
75
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6 answers
If like charges repel, why doesn't a charge break itself apart?
How can it be that, if like charges repel, they don't repel themselves? In other words, why don't charges break apart?
About the possible duplicate: I want to know about charges in general, not just that of an electron.
My response to Lawrence B.…
Kevin
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5 answers
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 photon field, but is this explanation enough? Do…
Newman
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70
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3 answers
Why is the ampere a base unit and not the coulomb?
I always thought of current as the time derivative of charge, $\frac{dq}{dt}$. However, I found out recently that it is the ampere that is the base unit and not the coulomb. Why is this? It seems to me that charge can exist without current, but…
Greg
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7 answers
Does a constantly accelerating charged particle emit EM radiation or not?
The Abraham-Lorentz force gives the recoil force, $\mathbf{F_{rad}}$, back on a charged particle $q$ when it emits electromagnetic radiation. It is given by:
$$\mathbf{F_{rad}} = \frac{q^2}{6\pi \epsilon_0 c^3}\mathbf{\dot{a}},$$
where…
John Eastmond
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57
votes
7 answers
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?
asmaier
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53
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6 answers
How did physicists know that there are two kind of charges?
Problems
The question I am about to make is either too stupid or hasn't bothered anyone because its obvious because I can't really find the answer anywhere.
I am currently studying electricity and magnetism and my book starts by telling that matter…
George Smyridis
- 3,011
52
votes
6 answers
Has anyone charged an object with 1 coulomb? Why was such a ridiculously large charge chosen as the unit of charge?
The fact that two balls charged with 1 coulomb each would repel/attract each other from a distance of 1 metre with a force sufficient to lift the Seawise Giant would suggest me otherwise, but has anyone ever charged an object with 1 coulomb of net…
moonblink
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50
votes
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Is there oscillating charge in a hydrogen atom?
In another post, I claimed that there was obviously an oscillating charge in a hydrogen atom when you took the superposition of a 1s and a 2p state. One of the respected members of this community (John Rennie) challenged me on this, saying:
Why do…
Marty Green
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43
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What is the net charge of the Earth?
This question arose in a seminar today about the solar wind...
This is my vagueish understanding of the problem - please correct if you see errors!
The 'classical' picture of atmospheric electricity is that the Earth as a whole is neutral, but that…
Hywel
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