When I get a text message on my mobile phone does it become slightly heavier?
No, it doesn’t.
Your message will be stored on a memory chip. The mass of this chip will not change appreciably whether electricity is running through it or not.
The same idea was addressed by the Straight Dope Science Advisory Board: If I remove data from my hard drive, why doesn’t it weigh less?
It becomes slightly lighter. It takes energy to receive and process the message, which comes out of the battery. Mass is energy, so less energy = less mass. Unless there is some gas exchange with the atmosphere - but cell phone batteries are sealed, I believe.
Oh come now. There will not be even a picogram of mass difference between a phone loaded with electricity and one that is completely dead.
An electron is, what? 1/1800 the mass of a proton, right? A spec of dust on the phone would weigh more than the difference in electrons.
Correct me if I’m wrong.
No! The battery’s mass remains the same.
A good analogy for the battery is a spring. If you put a spring under a heavy object so it is compressed, then the spring has energy stored in it. But the spring’s mass is always the same.
No, I believe that the number of electrons remains more-or-less the same. The difference is that they have gone from the negative part of the battery to the positive. When you recharge a battery you move those electrons back to the negative part, much like loading a spring.
No, it isn’t. You and Aeschines are both forgetting about e=mc[sup]2[/sup]. This equation does not just apply to nuclear reactions, but to anything where energy is stored and released, including batteries and springs. The difference may not be measurable with current technology, but it is real and calculable.
Not I. I recognize that the phone’s using electricity causes it to lose mass.
But, assuming the OP is really serious about the question, the mass is so infintessimally small that it is irrelevent.
E=mc[sup]2[/sup] also tells us that even a single atom converted 100% into energy would result in a very large quantity of energy. Contrariwise, you can use enormous amounts of energy without even removing an atom’s worth of mass.
Not really. Let’s tak a carbon-12 atom, for instance. The 12 means that one mole of C-12 will mass 12 grams, or .012 kg. Since there are 6.022 x 10[sup]23[/sup] atoms per mole, one atom masses 1.99 x 10[sup]-26[/sup] kg. If we plug that into e=mc[sup]2[/sup], we get e=1.99 x 10[sup]-26[/sup] [sup].[/sup] (3.00 x 10[sup]9[/sup])[sup]2[/sup] = 1.79 x 10[sup]-9[/sup] joules. That’s pretty small. But then, so is an atom.
I think you’re wrong here. Admittedly, I dropped out two years into my physics degree, so maybe they hadn’t gotten to that part.
Mass is not energy and energy is not mass. They are interchangeable according to the equation e=mc[sup]2[/sup], but only in nuclear reactions. Energy released from a battery is a conversion from chemical energy to electrical, then to mechanical or heat or light energy. No electrons are gained or lost.
This is my understanding, but if anyone’s got a cite, I’ll admit defeat.
Hey, I never said there would be a measurable difference. But according to my calculation, a 6V 1200 mAh battery gains about 300 picograms when fully charged.
Even a uranium atom converts to less than 4x10[sup]-8[/sup] Joule of energy. I wouldn’t call that “enormous amounts of energy.” Atoms are tiny.
Yes they are. The Equivalence of Mass and Energy:
From the Master
Well, I stand corrected.