Are charged batteries heavier?

[rootone]

Since you can add energy to a battery then extract it later, considering mass energy equivalence, it should be more massive, no?
Somehow that doesn't make sense though.

 

[phyzguy]

It is more massive. Let's calculate how much. The battery on my laptop stores about 50 W-h = 180,000 Joules. Δm = ΔE/c^2 ~= 2 picograms. Hard to measure!

 

[rootone]

Thanks and yes it would be hard to measure but not impossible.
I expect somebody will be able to confirm that this has been checked out.

 

[phyzguy]

Of course mass-energy equivalence has been checked in many different ways. Here's one for example. But I don't think there is any scale accurate enough to measure the mass difference between a charged and uncharged battery.

 

[rootone]

Interesting link.
I heard also about the planes flying in different directions as well, although I think that is GR rather than SR.
Back to batteries though, if they become more massive when charged, even by an immeasurably small amount, where is the extra mass?
Do electrons get more massive?

 

[Nugatory]

Interesting link.
I heard also about the planes flying in different directions as well, although I think that is GR rather than SR.

Are you thinking of Hafele-Keating? https://en.wikipedia.org/wiki/Hafele–Keating_experiment

Back to batteries though, if they become more massive when charged, even by an immeasurably small amount, where is the extra mass?
Do electrons get more massive?

The battery as a whole is more massive; you can't assign the extra mass to anyone part of it. The mass of the charged battery is greater than the sum of the masses of its constituent parts.

 

[rootone]

1 Yes that is the experiment I heard of.

2 Aggregated mass of constituents is something I need to think about,.

 

[Dale]

where is the extra mass?
Do electrons get more massive?

The molecules in a charged battery are different than the molecules in an uncharged battery. The ones in the charged battery are more massive than the ones in he uncharged battery. You cannot assign the mass to any part of the molecules, just the molecules as a whole.

 

[rootone]

The molecules get more massive.

How?

 

[Dale]

How?

By being in a configuration with more potential energy.

 

[rootone]

OK I get the idea.
But what exactly is configuration?
Something to do with Higgs field?

I am puzzled, but hey that's why I am here,

 

[Dale]

But what exactly is configuration?
Something to with Higgs field?

No. For a chemical reaction it is just electromagnetic. The Higgs is not relevant.

Configuration means the various distances between nuclei and electron orbitals etc. That is what gives chemicals their energy.

 

[DrClaude]

Since you can add energy to a battery then extract it later, considering mass energy equivalence, it should be more massive, no?

Slightly off-topic comment: this is something that irks me about many sci-fi stories. Some devices, such as weapons, have an incredibly big energy supply, but are still lightweight. Not possible, $E=mc^2$ rules!

 

[CWatters]

Not sure if it's possible to weigh something like a smartphone battery to within 2 pico grams? I know you can weigh much smaller things more accurately but i don't think the method used for that can be applied to something big like a battery.

According to Wikipedia the international standard kilogrammes gains around about 1 micro gram a month by absorbing contaminants from the air despite being under two nested bell jars. That works out at about about 33 Pico grams a day.

 

[mjc123]

An exception would be the lithium-air battery, which uses oxygen from the atmosphere to oxidise lithium in the discharge reaction:
2Li + O₂ → Li₂O₂
As the oxygen comes from the atmosphere on discharge and is released to it on charge, it is not part of the battery, which therefore weighs more in the discharged state than the charged state.

 

[CWatters]

I did wonder is some sort of balance could be created using an ink jet cartridge...

Ink jet cartridges create pico litre droplets of ink so I was thinking that perhaps you could use one to squirt ink onto a counter weight until it was in balance with a discharged battery. Then charge the battery using a wireless charger and count how many additional drops are required to bring it back into balance again.

Then I realized that the tiny drops produced by an ink jet printer would be three orders of magnitude too big! (pico Liters >> pico grams)

 

[Andy Resnick]

Of course mass-energy equivalence has been checked in many different ways. Here's one for example. But I don't think there is any scale accurate enough to measure the mass difference between a charged and uncharged battery.

Minor quibble (since I'm an experimentalist): I think you mean 'precise', not 'accurate'. This measurement, for example, requires about 14.5 significant figures (to reliably measure 1 pg changes in a 100g battery). I don't know any existing balance that can do this (maybe the Watt balance). The standard kilgoram calibration campaign quotes about 11 digits (1 ug/kg) using one of these:

https://www.mt.com/dam/P5/labtec/08...tion/03_Datasheet/DS_Vacuum_M_one_M_10_EN.pdf

 

[256bits]

Minor quibble...

For absolute mass measurement.
But what about mass difference.
Using a Cavendish torsion balance, the period of oscillation should be comparable to the square root of the difference in mass, or rather 10^-6 seconds, and that 'should be' fairly easy to measure with a current time clock.
Just wondering.

 

[Khashishi]

Check out https://en.wikipedia.org/wiki/Binding_energy

The binding energy can sometimes be interpreted as a reduction of field energy. For example, an electron and a proton are bound as a hydrogen atom. The electric field has energy $\frac{1}{2}\epsilon E^2$. When the electron and proton are close together, the E fields overlap and mostly cancel out, reducing the field energy. By rearranging the atoms in matter, you can change the energy even though the number of atoms is equal.

 

[Andy Resnick]

Using a Cavendish torsion balance, the period of oscillation should be comparable to the square root of the difference in mass, or rather 10^-6 seconds, and that 'should be' fairly easy to measure with a current time clock.
Just wondering.

Why go through the effort? The uncertainty/statistical spread of a discharged battery's mass is likely many times larger than a pg.

Edit- I just realized, how did you get 10^-6 seconds fractional difference for the oscillation period?

 

[CWatters]

Why go through the effort? The uncertainty/statistical spread of a discharged battery's mass is likely many times larger than a pg.

Why is that a problem? Wouldn't you would measure the frequency of oscillation of _a_ battery while it was being discharged looking for the change in mass.

 

[Andy Resnick]

Why is that a problem? Wouldn't you would measure the frequency of oscillation of _a_ battery while it was being discharged looking for the change in mass.

How would you discharge it while in the device? How much of an effect would you expect to see?

 

[DaveC426913]

No. For a chemical reaction it is just electromagnetic. The Higgs is not relevant.

Configuration means the various distances between nuclei and electron orbitals etc. That is what gives chemicals their energy.

So, to bring this back to the OP's question:
the inflow of electricity, in the form of electrons, causes molecules to change shape, and some of the electrons' orbital energy is converted back to mass ... by way of muons?

Or am I word salading here?

 

[bland]

See a battery on table, put a table mat underneath the battery and wa la, battery weighs more. Not a lot more, I'll give you that!

 

[phyzguy]

Why is that a problem? Wouldn't you would measure the frequency of oscillation of _a_ battery while it was being discharged looking for the change in mass.

If you think this measurement is feasible, why don't you go ahead and give it a try? I concur with Andy Resnick. No measurement technique exists that can measure a change in mass of 1 part in 10^14.

 

[bland]

Something to do with Higgs field?

A common misconception, the Higgs field is only responsible for about 1% of the mass of an atom,

Explained here by Frank Wilczek...


Full video here http://techtv.mit.edu/videos/15942-the-origin-of-mass-and-the-feebleness-of-gravity

Somehow that doesn't make sense though.

Why stop there, if you think about it nothing makes sense. For example, once upon a time there was a huge cloud of molecular hydrogen and not much else, then by a convoluted series of condensations a conscious being emerged wondering why things don't make sense.

 

[Dale]

by way of muons?

No, why would there be muons? There are no nuclear reactions or cosmic rays in a battery.

 

[DaveC426913]

No, why would there be muons? There are no nuclear reactions or cosmic rays in a battery.

Yeah. Word salad.

I was thinking that the change of an electron between orbitals would involve a particle energy-mass conversion.

 

[rootone]

once upon a time there was a huge cloud of molecular hydrogen and not much else, then by a convoluted series of condensations a conscious being emerged wondering why things don't make sense.

Thanks for those.
Are you related to Douglas Adams by any chance?

 

[Nugatory]

So, to bring this back to the OP's question:
the inflow of electricity, in the form of electrons, causes molecules to change shape, and some of the electrons' orbital energy is converted back to mass ... by way of muons?

No, it's much more straightforward than that. The mass of a multi-particle system is generally not equal to the sum of the masses of the particles of which it is composed.,

 

[CWatters]

If you think this measurement is feasible, why don't you go ahead and give it a try? I concur with Andy Resnick. No measurement technique exists that can measure a change in mass of 1 part in 10^14.

Oh I don't think it's feasible I just didn't understand why differences between batteries would be the problem if only one is used.

 

[bland]

The mass of a multi-particle system is generally not equal to the sum of the masses of the particles of which it is composed.,

Which is fundamentally why atoms and molecules form, because like water nature generally wants to live on the ground floor.

 

[DrClaude]

Which is fundamentally why atoms and molecules form, because like water nature generally wants to live on the ground floor.

That's not correct. Energy is not the relevant quantity, its entropy!

 

[Dale]

I was thinking that the change of an electron between orbitals would involve a particle energy-mass conversion.

It does, but the particle in question is the whole atom or molecule, not the electron. An excited atom is more massive than an atom in the ground state. In the transition the energy is lost to photons and/or KE.

 

[256bits]

Δ√QUOTE="Andy Resnick, post: 5951029, member: 20368"]The uncertainty/statistical spread of a discharged battery's mass is likely many times larger than a pg[/QUOTE]
Looking at a harmonic oscillator, torsional:
Originally, I had thought that since the period is proportional to the square root of the mass, ... could be faulty thinking.

Background:
Time period of oscillation of twisting wire,
https://www.colorado.edu/physics/phys1140/phys1140_sp05/Experiments/M4Fall04.pdf

or frequency,
ω = √[ (^k/_I )
I - moment of inertia of the mass(s)

https://en.wikipedia.org/wiki/Cavendish_experiment

For the Cavendish balance,
This is the regular formula, for two masses separated horizontal distance 2L, and hanging from a wire.

T -period
m - mass
L - distance to wire
k - torsion coefficient of the wire

The mass hanging from the wire could be a single battery, or two on extended arms similar to the Cavendish setup.

We should have, with the battery uncharged
T₁ = C√( m )
where C is a constant composed of 2, π, √L²/_2k

Similarly, with the battery charged,
T₂ = C√( m + Δm )

Squaring each equation, and subtracting
T₁2 - T₂² = C² Δm

or
Δm = T₁2 - T₂² / C²

Like you said could be impractical due to errors in measurement for C.

 

[DaveC426913]

It does, but the particle in question is the whole atom or molecule, not the electron. An excited atom is more massive than an atom in the ground state. In the transition the energy is lost to photons and/or KE.

I've struggled with this on and off over time.

(I know this is a digression, since now I'm invoking nuclear reactions, but humor me for a moment.)

When a nucleus f̶i̶s̶s̶e̶s̶ undergoes fission, and loses mass, that mass is carried away by a particle moving very fast. If I have read correctly, the momentum of that particle (which incorporates its KE) will account for the mass missing from the end product. True?

Does this mean that the energy that the mass was converted from is KE? No mysterious other energy emitted?If so, is the same momentum at work in a molecular reaction? i.e, is the change in the KE of the various particles factored into the equation?

(I'd better go back and read my books. This stuff is slipping out of my head. Actually ,maybe I'd better pick up some new books.)

 

[bland]

When a nucleus f̶i̶s̶s̶e̶s̶ undergoes fission, and loses mass, that mass is carried away by a particle moving very fast. If I have read correctly, the momentum of that particle (which incorporates its KE) will account for the mass missing from the end product. True?

I believe this is what Lise Meitner understood when she helped her previous subordinates back in Germany understand what was happening. She calculated that the missing mass had indeed become the kinetic energy of the split atom pieces.

 

[jartsa]

I've struggled with this on and off over time.

(I know this is a digression, since now I'm invoking nuclear reactions, but humor me for a moment.)

When a nucleus f̶i̶s̶s̶e̶s̶ undergoes fission, and loses mass, that mass is carried away by a particle moving very fast. If I have read correctly, the momentum of that particle (which incorporates its KE) will account for the mass missing from the end product. True?

Does this mean that the energy that the mass was converted from is KE? No mysterious other energy emitted?If so, is the same momentum at work in a molecular reaction? i.e, is the change in the KE of the various particles factored into the equation?

(I'd better go back and read my books. This stuff is slipping out of my head. Actually ,maybe I'd better pick up some new books.)

Nature's conservation laws say that a box filled with matter and anti-matter and weighing 1 kg can become a box filled with radiation and weighing 1 kg.

The law of conservation of mass demands that the total mass of the box does not change.

In that annihilation process matter became radiation. Those two things, matter and radiation, have the same mass, if we assume that the mass of the container stays the same.

("Radiation" can be replaced e.g. by charged batteries. "Matter and anti-matter" can be replaced e.g. by nuclear plant)

Quantum mechanics: "If cat's transformation to a dog does not violate conservation laws, then the transformation happens with some probability"

 

[Tom Kunich]

It is more massive. Let's calculate how much. The battery on my laptop stores about 50 W-h = 180,000 Joules. Δm = ΔE/c^2 ~= 2 picograms. Hard to measure!

Has anyone ever told you what a spoil sport you are?

 

[phyzguy]

Has anyone ever told you what a spoil sport you are?

Oh well. Reality has a way of intruding on some of the best ideas.

 

[SongDog]

@CWatters, you might want to re-read that Wikipedia entry more closely.

 

[anorlunda]

Several posters in this thread talked about the relationship between mass and energy. If the OP had chosen a gas-filled bottle instead of a battery, the complex talk about molecules in this thread could have been avoided.

For example, a scale would measure the kinetic energy of the molecules in a bottle of gas to be part of invariant mass of the bottle, and thus also its rest mass.

So if a the gas in the bottle is warmed, it weights more. No atomic/molectular effects are necessary.

I think the easier way to think about it is that energy gravitates. But it can be very tricky. KE is frame dependent. So if all the particles in the bottle move the same direction, their KE is zero in some rest frame, and there is no invariant mass. But if they move in many directions, there is an invariant KE and an invariant mass associated with the KE.

From the same wiki article:

Note that for reasons above, such a rest frame does not exist for single photons, or rays of light moving in one direction. When two or more photons move in different directions, however, a center of mass frame (or "rest frame" if the system is bound) exists. Thus, the mass of a system of several photons moving in different directions is positive, which means that an invariant mass exists for this system even though it does not exist for each photon.

 

[PAllen]

Several posters in this thread talked about the relationship between mass and energy. If the OP had chosen a gas-filled bottle instead of a battery, the complex talk about molecules in this thread could have been avoided.
So if a the gas in the bottle is warmed, it weights more. No atomic/molectular effects are necessary.

I think the easier way to think about it is that energy gravitates. But it can be very tricky. KE is frame dependent. So if all the particles in the bottle move the same direction, their KE is zero in some rest frame, and there is no invariant mass. But if they move in many directions, there is an invariant KE and an invariant mass associated with the KE.

From the same wiki article:

And on this score, there is experimental evidence:

https://arxiv.org/abs/gr-qc/9909014

Part of this paper reanalyzes existing experiments to establish that kinetic energy has weight.

 

[Redbelly98]

When you connect a battery to a charger, some material from the connectors can transfer from the charger's connector leads to the battery terminals. Or material from the battery terminals can get transferred to the connectors. Then when the battery is connected to a device and discharged, the same thing can happen.

As a result, a charged battery has about a 50% chance of being more massive than a discharged one. :-)

 

[mfb]

For absolute mass measurement.
But what about mass difference.
Using a Cavendish torsion balance, the period of oscillation should be comparable to the square root of the difference in mass, or rather 10^-6 seconds, and that 'should be' fairly easy to measure with a current time clock.
Just wondering.

The period of oscillation is proportional to the square root of the total mass. You don't have anything that is directly sensitive to a mass difference of the same object at different times. There is no known way to repeat the Cavendish experiment with a 10^-14 accuracy. If there would, we wouldn't have such a large uncertainty for the gravitational constant.

The best relative gravimeters reach a ~10^-12 sensitivity. Heating something can change the mass by ~10^-12 - but not if you want to keep it superconducting, as required by the gravimeters. We are maybe 1-2 orders of magnitude away from measuring a mass change from a temperature change. The mass change of a battery is even smaller.

 

[Stephenk53]

This reminds me of the discussion on Chief delphi about whether or not adding code to a robot increases mass

 

[rkolter]

Since you can add energy to a battery then extract it later, considering mass energy equivalence, it should be more massive, no?

Yes.

Energy and mass can be converted into each other and are equivalent. But, the conversion factor is the square of the speed of light. Hydrogen bombs convert mass to energy - a little mass makes a lot of energy. Charging a (sealed) battery converts a little bit of energy to mass - and a little bit of energy makes a miniscule amount of mass.

It is more massive. Let's calculate how much. The battery on my laptop stores about 50 W-h = 180,000 Joules. Δm = ΔE/c^2 ~= 2 picograms. Hard to measure!

To put phyzguy's value into perspective, from 2010 to 2017 there have been, give or take, about 1.5 billion laptops sold. Pretend all those batteries could hold the same charge... if you measured the mass of all the batteries sold with laptops from 2010 to 2017 uncharged, and then charged them all, and measured the mass precisely again, you would find the 1.5 billion batteries gained about 3 grams of mass total.

 

[PAllen]

Picking up a battery to put it on a scale will transfer many orders of magnitude more mass from your fingerprints than the increase due to charging it.

 

[jerromyjon]

What if instead of weighing batteries, you could prove one was lighter and by roughly how much...

 

[jerromyjon]

Hydrogen bombs convert mass to energy - a little mass makes a lot of energy.

and a little bit of energy makes a miniscule amount of mass.

Way to put it into perspective.