Does an electrical charge have weight?

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__dan

Senior Member
electrons have mass

electrons have mass

electrons have stable mass. If there are theories where the electron gets lighter, it's not from charging in a battery.

Photons have no mass, adding photons to an electron does not affect mass.

The battery electrolyte has specific gravity and a change in density from charging. Charging the battery causes the electrolyte to becomes less dense, it occupies more space at the same mass (I could easily have that backwards, I know charging affects density, specific gravity). The battery plates (one of them) gets a coating from charging, it looks like a dusting with charcoal dust when fully charged on, I am guessing, the positive plate.

Adding electrons to a cap adds the weight of the additional electrons.
 
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mivey

Senior Member
Forgetting the finer details and looking from a big picture standpoint, you have added energy to a system so the net mass would increase as well.
 

Cold Fusion

Senior Member
Location
way north
Does a fully charged cap, wiegh more than an uncharged cap?

Does a charged battery wiegh more?
Well, Eric Weisstein say an electron has a mass of
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Disclaimer: As for if a charged cap weighs more, particle physcis is a bit out of my area.

1 coulomb = 1.60 x 10^19 electrons. So the electrons in 1 amp-second is 6 X 10^(-12) kg. not a lot of weight.

cf
 

Cold Fusion

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Location
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Disclaimer 1: Same as before about particle physics

Looking at caps:
If you connect one lead of a battery to a cap and leave the other lead in open air - no current flows

Now if you connect one lead of a cap to a battery positive and the other lead to the batt negative and put an ammeter in each lead, the same current flows in both leads. So, however many amp seconds flows in one end of the cap flows out of the other. The net number of the electrons in the cap didn't change. We just pulled the electrons from one plate and stacked them up on the ther plate.

I'd say it weighs the same.

Theoretical Physics disclaimer: I have about the same amount of knowledge about theoretical physics as I do about particle physics.

I don't know what weight is added to a cap by stressing the electric field between the two plates. I'm not sure Einstein equation fits. But if it did:

Charging a 2F cap to 1V takes 1 Joule of energy. Per Einstein 1J would weigh abour 1 x 10^(-17)kg Could be hard to measure.

I don't know nuthin' about what happens to the electrons in the acid and plates in internal battery chemistry.

cf
 

StephenSDH

Senior Member
Location
Allentown, PA
A capacitor doesn't store electrons like a balloon. For it to be "Charged" one side of the capacitor would be more positive and the other side would be more negative. For the capacitor to store more electrons the average charge of both sides of the capacitor would need to have a charge greater then some other reference point. Basically a static charge.

So it might as well be anything with a negative static charge weighs more then being grounded, like balloon after rubbing it on your head.
 

broadgage

Senior Member
Location
London, England
Electrons do have weight, though it is minute and unlikely to be of any practical importance whatsoever.

A charged battery or capacitor should have exactly the same weight as an uncharged one, since it contains the same number of electrons.
They are merely differently distributed between the positive and negative plates.

An article with a negative static charge should weigh more than a similar uncharged article since it contains more electrons.
The difference would probably be too small to be readily detectable.
 

Rick Christopherson

Senior Member
From non-relativistic physics, a charged capacitor weighs exactly the same as an uncharged capacitor, because the electrons have simply switched sides, but the total is unchanged.

There are those that purport that an increase in energy state will result in an increase in mass due to relativity, but the effects are so astronomically negligible, even on an atomic level, that this is a bit asinine. It is typically presented by those that want to show off their alleged knowledge, not for real effect.
 

nakulak

Senior Member
the likelihood of anyone having the instrumentation (if it exists) necessary to determine the difference in weight between any normally used devices is so incredibly unlikely, for all practical purposes there is no difference in weight (weight being a function of mass). i would think any ordinary instrumentation would be more likely to give an erroneous reading due to attraction of charged bodies (which I would expect the force to be orders of magnitude greater than gravitational attraction). Of course, as always, jmshio
 

steve66

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a charged capacitor weighs exactly the same as an uncharged capacitor, because the electrons have simply switched sides, but the total is unchanged.

I agree. I would expect the same principle to apply to a battery, but I'm not 100% sure.

It was a very good question, but it also reminds me of the time Dilbert told his boss his laptop computer would be lighter if he deleted unnecessary files:)

Steve
 

gar

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Occupation
EE
091125-1024 EST

E = M*C^2 has nothing to do with the original question. This applies to the transformation of mass into energy or vice versa. In the question presented there is no conversion of energy into mass.

An electron has mass. This is demonstrable in a magnetron or cyclotron.

If I have something and add electrons to it, then there is a small increase in mass.

If I have an insulator that I remove electrons from one side and move these to the other side, then there is no change in mass.

If I raise a mass of one pound one foot there is no change in mass, but there is an increase in its potential energy. There is also a minute change in the force on the one pound mass resulting from the change in position relative to the center of mass of the earth. So if you weigh the one pound mass at sea level and then raise it to 100,000 ft you will see a noticeable change in its weight.

.
 

charlie b

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Lockport, IL
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Retired Electrical Engineer
An electrical charge does not have weight. Charge is a property that is possessed by an electron, and the electron itself has weight. The question is the same as asking if age has weight. OK, I am a person, and one property, or characteristic, that I possess is that I have weight. As I age, my weight may change. But that is not because age itself has weight, and the change in age has caused the change in weight. In the same sense, charge does not have weight.
 

skeshesh

Senior Member
Location
Los Angeles, Ca
An electrical charge does not have weight. Charge is a property that is possessed by an electron, and the electron itself has weight. The question is the same as asking if age has weight. OK, I am a person, and one property, or characteristic, that I possess is that I have weight. As I age, my weight may change. But that is not because age itself has weight, and the change in age has caused the change in weight. In the same sense, charge does not have weight.

I agree that the question was not worded properly. But anyway yes an electron has mass. A charged capacitor should not experience change in mass unless something really weired, modern-physics-end-of-chapter-questiony stuff's been done to it. As far as "relativistic mass", I find it hard to apply to this conversation. It's true that there's the whole "rest mass"*gammafactor = "relativistic" in particle physics, but most often the situation is looking at a free particle traveling in a strange vaccum space, and I really don't remember a single time where this stuff was related to classical physics of motion much less electricity when I was in school. In fact the only time we stepped out of the realm of the absurd was learning how vaccum tubes were used and how it led to the transistor and that whole shpeel. Wow... just thinking about is again getting me pissed off about how much worthless crap I learned in school and how much great stuff was omitted...
 

mivey

Senior Member
From non-relativistic physics, a charged capacitor weighs exactly the same as an uncharged capacitor, because the electrons have simply switched sides, but the total is unchanged.

There are those that purport that an increase in energy state will result in an increase in mass due to relativity, but the effects are so astronomically negligible, even on an atomic level, that this is a bit asinine. It is typically presented by those that want to show off their alleged knowledge, not for real effect.
This whole topic is about things on the atomic level. The change in mass may not have anything to do with the change in particle count. What is going on at the atomic level is the real effect.

To dismiss the topic because you can't plop it down on your bathroom scale and see it is asinine.
 
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