Originally posted by RamnedWell I'll take a shot, but it's probably wrong... Proton volts would be the same magnitude as electron volts, just negative. I think protons have the same amount of charge, just opposite. I'm sure there's much more to it than this given the degree of difficulty of the previous questions, but I figured I'd get it started. 🙂
Electrical Energy / Capacitance
[b]16. Suppose scientists had chosen to measure small energies in proton volts rather than electron volts. What difference would this make and why?[/b]
Originally posted by RamnedNo, I mean before you stick it on the wall. How does rubbing the balloon on the carpet (or your head) give it excess negative charge? Why doesn't the carpet (or your head) get the excess negative charge?
This is what's going on. The balloon induces a charge of opposite sign int the wall, causing the balloon and wall to be attracted to each other. The balloon eventually falls because its charge slowly diminishes as it leaks to the ground. (Some of the balloon's charge also could be lost due to positive ions in the surrounding atmosphere, wich would tend to neutralize the enegative charges on the balloon caused by the wall.)
Ok. 16 to follow.
It's actually a pretty tricky question. I looked it up when you asked, because I didn't know it right off. What I found was that when you rub the balloon against something, like your shirt or hair, the electrons on your shirt (or hair) prefer to stick to the molecules in the balloon more than to you. It seems that certain materials are more likely to "hold" electrons, and some more likely to "give" them. The site I found suggested, for the strongest transfer, to rub fur on vinyl. Sounds like a homemade physics experiment to me.
The website also cautioned that friction is NOT the reason why electrons transfer; an example they gave was sticking tape to a surface and pulling it off, then put your finger near, but not touching, the tape. It should be attracted to your finger by static electricity!
Originally posted by XZantothElectron volt = kinetic energy of an electron accelerated though one volt.
Well I'll take a shot, but it's probably wrong... Proton volts would be the same magnitude as electron volts, just negative. I think protons have the same amount of charge, just opposite. I'm sure there's much more to it than this given the degree of difficulty of the previous questions, but I figured I'd get it started. 🙂
For a proton, the charge is the same, so the force would be the same (except opposite). But the mass is greater. Therefore the final velocity would be less. The momentum, mv, would be the same, but kinetic energy is mv^2/2. So a proton volt would be less than an electron volt.
[I don't think it would make sense to say it was negative - the kinetic energy can't be negative. So you might need to tweak the definition a bit]
I think!
As for what difference it makes, well nothing, really! Not in terms of what happens. You don't change the physics by changing the units of measurement.
Originally posted by mtthwYes - that's right. Makes no difference if scientists were to change, except opposite directions...
Electron volt = kinetic energy of an electron accelerated though one volt.
For a proton, the charge is the same, so the force would be the same (except opposite). But the mass is greater. Therefore the final velocity would be less. The momentum, mv, would be the same, but kinetic energy is mv^2/2. So a proton volt would be less than an elect ...[text shortened]... in terms of what happens. You don't change the physics by changing the units of measurement.
Next one to come.
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Originally posted by RamnedThe velocity would increase, assuming no "resistance." The flow of current would increase.
Current and Resistance
[b]17. What could happen to (A) the drift velocity of the electrons in a wire and (B) to the current in the wire if the electrons could move freely without resistance?[/b]
The qualifier on "resistance" is because there isn't really resistance the way that brakes brake a car or water flows through a pipe. The electrons jump from ion to ion in a current. When one electron is moved out another one is attracted to make the jump. So, I'm not sure that taking away all resistance is anything more than a theoretical non-existent conception. However, i know absolutely NOTHING about electricity except for it's the stuff that comes through the plugs in the wall.
Originally posted by sven1000Thanks, sven1000!
It's actually a pretty tricky question. I looked it up when you asked, because I didn't know it right off. What I found was that when you rub the balloon against something, like your shirt or hair, the electrons on your shirt (or hair) prefer to stick to the molecules in the balloon more than to you. It seems that certain materials are more likely to "ho ...[text shortened]... but not touching, the tape. It should be attracted to your finger by static electricity!
Originally posted by RamnedDrift velocity is determined by the current, so it makes more sense to address what happens to the current first.
Current and Resistance
[b]17. What could happen to (A) the drift velocity of the electrons in a wire and (B) to the current in the wire if the electrons could move freely without resistance?[/b]
Current (I) will only flow if there is an electric field (i.e. a voltage drop (V) across the wire). According to Ohm's law, V=IR, so as R approaches zero I will approach infinity. However, the actual velocity would likely be capped at c, unless the fictional material used to make the resistanceless wire also has properties which suspend other laws of nature.
Originally posted by coquetteActually, you're right. Frift velocity increases b/c collisions would be nonexistant. I is proportional to drift velocity, so current will rise too.
The velocity would increase, assuming no "resistance." The flow of current would increase.
The qualifier on "resistance" is because there isn't really resistance the way that brakes brake a car or water flows through a pipe. The electrons jump from ion to ion in a current. When one electron is moved out another one is attracted to make the jump. So, I'm ...[text shortened]... ING about electricity except for it's the stuff that comes through the plugs in the wall.
