Mobile Phones weight more when Charged

No. Where do you think the extra weight comes from? The battery is sealed right. It's not from electrons going into the battery either.

Yes. They do weigh a tad more, though I doubt it's enough to notice. john

I'm guessing it's just psychological in Phil's case. The weight of the energy (ala e=mc^2) would be, uhhh, about 20 kJ = 0.0000000002 grams.

Some battery chemistries use the surrounding air in their reaction, don't they? So if you had a zinc-air cell phone battery, might it weigh more when charged? Doubtless still too little to detect without an instrument, though.

When exhausted perhaps? As air combines with the zinc?

Yes, E=mc^2

Odd, the difference shouln't be noticable (or even measurable)

Bye. Jasen

Is E=mc^2 actually applicable here? I think not... What it actually says is that when an energy E is 'converted' into an equivalent mass you get a mass m=E/(c^2). Here in this case, the energy is stored as energy itself - as electrostatic energy between the terminals of the battery. The charges too do not get 'introduced'. They just get unbalanced so that they have to use the external circuit we are going to connect to get balanced. So it seems that no mass gets added, either due to the energy added or due to charge seperation. This can't account for the mobile feeling heavier, but may be there's some complicated reason for that one, or may be it's simply psychology...

it is.

???

no, as chemical potential energy - reconfigured molecules inside the cells.

Bye. Jasen

Yep. As soon as relations between particles change and because of that total energy changes, total mass changes. No loopholes have been found anywhere in physics.

Black holes? Vortexes?

You have a problem with black holes and vortices in your batterycharger? And those are not loopholes in energy storage and conversion.

Cell phones seem to weigh the least when fully charged and the most when battery is dead. Haven't you noticed that even the most rabid cell talker eventually tires of holding that silly blob against his/her head and that nobody cares to do that at all when the battery is depleated?

No, a fully charged "cell" is heavier than a dead one, for the same reason that a freshly washed and waxed car runs better than a dirty one.