Lohrenswald
世界的 bottom ranked physicist
Do anyone have information on the whole gravitational waves news thing?
Electricity puzzles me.
There's speak of negative and positive charges, but in reality there's a fixed array of nuclei with electrons able to move, and positive charges are just the lack of electrons, right? Then there's the principle that in conductor the excess charge goes to the surface. If it's positive that would mean that in reality the electrons would leave the surface.
Why would they do so if they repel each others? Wouldn't it be more reasonable that the surplus negative charge goes to the surface, but if there's lack of electrons, they are equally distributed in the whole conductor?
This might be because it's electrostatics. So, the explanation would be that it's not a statical situation?
That explanation also bugs me, since I have no reason to think there are any electrostatic situations. Of course that is irrelevant to the things that assume it, but what if I deal with a real life problem. How do I know that the electrons aren't on the move?
Then also, another question: suppose you have a solid metal ball of radius 1 m that is cocentric with an insulator sphere of radius 1.0001 m. They both have the same charge, equally spread out in the insulator. Is the charge in the conductor on it's surface, or just a little shy of it since the repelling force of the charge in the insulator?
Okay, one more: Suppose you have a charged solid metal ball. The argument for the interior having 0 electric field is that otherwise there would be a force acting on the charges, and the situation wouldn't be static (at least that's what Young and Freedman say). Couldn't there be a force that's radially outward from the center of the ball? You could even imagine it being there because of one single electron. The same force that keeps the charge on the surface (and doesn't allow it to fly away) keeps them on the surface in this scenario.
These were probably a little stupid questions, but I feel like many people have similar difficulties in understanding and in making it explicit too.
Electricity puzzles me.
There's speak of negative and positive charges, but in reality there's a fixed array of nuclei with electrons able to move, and positive charges are just the lack of electrons, right?
Then there's the principle that in conductor the excess charge goes to the surface. If it's positive that would mean that in reality the electrons would leave the surface. Why would they do so if they repel each others? Wouldn't it be more reasonable that the surplus negative charge goes to the surface, but if there's lack of electrons, they are equally distributed in the whole conductor?
This might be because it's electrostatics. So, the explanation would be that it's not a statical situation?
That explanation also bugs me, since I have no reason to think there are any electrostatic situations. Of course that is irrelevant to the things that assume it, but what if I deal with a real life problem. How do I know that the electrons aren't on the move?
Then also, another question: suppose you have a solid metal ball of radius 1 m that is cocentric with an insulator sphere of radius 1.0001 m. They both have the same charge, equally spread out in the insulator. Is the charge in the conductor on it's surface, or just a little shy of it since the repelling force of the charge in the insulator?
Okay, one more: Suppose you have a charged solid metal ball. The argument for the interior having 0 electric field is that otherwise there would be a force acting on the charges, and the situation wouldn't be static (at least that's what Young and Freedman say). Couldn't there be a force that's radially outward from the center of the ball? You could even imagine it being there because of one single electron. The same force that keeps the charge on the surface (and doesn't allow it to fly away) keeps them on the surface in this scenario.
And remember that in a static situation, Gauss's law says that the electric flux out of a surface is equal to the charge enclosed (divided by the permittivity) and thus without charges enclosed, the electric field is zero.
I hated taking electromagentism lmao But it's not as bad as thermodynamics. That I abhor.
If you drop a basketball, it bounces back up again, but not as high it was dropped from. The potential energy transforms into kinetic energy, which in turn transforms to heat of the floor, e.g. the kinetic energy of it's vibrating particles.
So, how does the wind chill work? I understand you can explain it by wind taking away heat from your body, but how does it work on the microscopic level? Shouldn't the air particles make atoms in your body vibrate? Okay, apparently when a molecule hits you, it begins to vibrate more, since it's looser than the molecules in your body, but why should that make the molecules in your body to vibrate less than before? Shouldn't it be at least random whether your body-molecules vibrate less or more after the collision?
Wind chill feels colder because it moves away the warm air around you, providing new cold molecules to suck heat from your skin.
I do understand the idea that a cold medium takes away heat faster than warmer one, but had difficulties on the mircolevel: how can a molecule suck heat, shouldn't it work like a basketball that hits the floor and cause the molecules in my body to vibrate more?
Based on what's said this far, I'd suppose that the air may heat your body by hitting it, but the effect of it carrying the cold air away is bigger.
Based on what's said this far, I'd suppose that the air may heat your body by hitting it, but the effect of it carrying the cold air away is bigger.
I do understand the idea that a cold medium takes away heat faster than warmer one, but had difficulties on the mircolevel: how can a molecule suck heat, shouldn't it work like a basketball that hits the floor and cause the molecules in my body to vibrate more?
Based on what's said this far, I'd suppose that the air may heat your body by hitting it, but the effect of it carrying the cold air away is bigger.