Now I understand completely.
An iPod is a series of tubes…
After pondering this some more. I am forced to conclude that I think beowulff is correct. There can be a small amount of net negative charge in the programmed flash for the reasons he has been talking about in this thread.
No, the iPod will tend to have no net charge. If it has a net positive charge, it will be attractive to electrons, and will gain them over time, losing its charge. If it has a net negative charge, it will repel electrons, and will lose them over time, losing its charge.
Ever rub a balloon in your hair and stick it to the ceiling? It won’t stay there forever, because it slowly loses its charge. The same thing will happen to an iPod. The fact that an iPod has flash memory is really a red herring, and has no bearing on whether the iPod will have a net charge.
When I first saw this OP in the list I would never have guessed that it would turn into another ‘plane on a conveyor belt’ one!
And yet Flash Memory works exactly like this. I thought the same thing when I set out. If you are running on a battery, then the charge in the floating gate transistor comes from the battery so there is no net charge on the device, but there is a net charge on the flash drive. It never loses the charge, because the electrons don’t have the energy to cross the barrier to escape. Put your balloon in a perfect insulator and the charge will stay on the balloon indefinitely.
There are wires (conducting lines of some sort, anyway) in the flash drive that are ultimately connected to the battery. You’re not going to have a situation where the flash drive as a whole has a negative charge, and the battery has a positive charge, because charge will flow from the battery to the conductors near the pockets of charge for every bit. You’ve got billions of these pockets, and wires inside the flash drive running near them all (how else are you reading the memory?). The separation of charge will be very small, and contained within the flash drive.
Put the balloon and perfect insulator inside an electrically neutral metal box. From the outside, you won’t be able to tell if the box itself is charged, or if it contains a charged balloon(*). If you touch a grounded wire to the box, it will give up charge until the box, the balloon, and the insulator taken together have zero charge. In a normal room environment, the box will still give up charge, it will just take longer.
(*) Maybe this is part of the misunderstanding. You can’t shield electric charge. A volume with a given total charge will will have an electric field “flowing” out of it (nonzero divergence; look up Gauss’s law). Put it in a metal box, you’ll still have the same total divergence. Drop it in a black hole, you’ll still have the same total divergence.
The “wires” are connected to the floating transistor by a semi-conductor or an insulator. They only get in and out of the transistor by quantum tunneling and they won’t do that until you apply a high enough voltage.
That is correct, and the charge on each of these transistors is so small as to be negligible.
The electric field that you claim can’t exist, changes the voltage threshold on the controlling transistor. The electrons in the floating transistor remain untouched.
I got the basic physics lesson. It’s why I came into this thread attempting to prove beowulff wrong. Maybe you should look up how flash memory works. If there are electron holes on the chip somewhere, I haven’t found it mentioned anywhere. It seems that the electrons being stored on the floating gate transistor come from the current which is supplied by the power source.
The wires are the blue bit and word lines in Flash Memory Basics on How Stuff Works. Or see figures 10-12 and 10-8 in FLASH MEMORY TECHNOLOGY (PDF). It’s not important how they connect to the transistors, just that they are conductive, and so short out any DC electric field on their surface.
Reread what I wrote: “The separation of charge will be very small, and contained within the flash drive.” I certainly never claimed an electric field can’t or won’t exist inside the flash memory.
The positive charges can be on the wires (Aluminum wires, per the PDF link, or the blue lines at the HSW link), or on on anything electrically connected to the wires. (My mp3 player has a metal back, free to give up lots of electrons. I suspect all mp3 players have some kind of metal chassis for shielding, to meet FCC interference regs.) You won’t see holes mentioned because no one talks about holes in conductors. The (conduction) electrons move freely, you just have more or fewer if the metal is charged. There are no pluses shown at the HSW link, but that’s just because where the positive charge is located is not important to how the memory works. You shouldn’t infer from that there is no corresponding positive charge in the flash drive.
For what it’s worth, I did an experiment last night. With my flash memory mp3 player on and playing, I attached its USB cable, but left the end that plugs into the computer free. I then charged it by touching one terminal of a 9 volt battery to the USB cable and the other terminal to a copper water pipe. I then switched the battery around to give the player the opposite charge. You know what happened? Nothing. So there doesn’t seem to be any necessity for an mp3 player to have a charge, and its corresponding additional mass (which is what the OP is asking about).
Thanks, I can use Google too. You’ll find all the same information and more on the wikipedia site. That HowStuffWorks site is useless.
I’ll buy that. It just seems odd that none of the papers on it mention it. It seems like an unusual thing to leave out when this question becomes pretty obvious. It does seem as if the electric field becomes problematic on scaling these things down, but even with the holes on the line there will be plenty of electric field to go around. What we really need is a cite that actually states this rather than a highschool physics lesson.
I was trying to figure out what type of field these things would have if they worked the way I had said earlier. I don’t have any actuall numbers though. I figure any one of these devices has somewhere from 10 to 100 electrons when charged. A large flash drive would probably have about a trillion of them. That’s about 10^14 electrons and that seems like it’s too large to operate that way. I’m going to have to say you are probably right, but there needs to be some more solid numbers since I’m just making them up.
Unfortunately, as far as I can tell you didn’t prove anything here.