0
$\begingroup$

This is probably a very basic to most of you physics people but It's frustrating me and I need to get answers ASAP.

Just saw an experiment on YouTube where they rub a silk on some sort of glass rod, and the rod becomes negatively charged. If you move it towards a positively charged balloon, the balloon will move towards the rod. This confuses me a lot. Positively charged means there are more protons than electrons, right? So when you move an negatively charged object, meaning more electrons, the electrons of the positively charged object will go to the other side away from the negatively charged object. I'm okay with that, but why does the protons (and the object) goes towards the side of the negatively charged object as seen on the visualizations, if protons doesn't actually move?

Please enlighten me.

$\endgroup$

3 Answers 3

2
$\begingroup$

but it is a fact that protons do not move

Hmm. Is it? Somewhere near half the mass of the balloon you mention comes from protons. The balloon moves, so wouldn't it be the case that the protons in the balloon move?

I think what you want to say is that the nuclei of atoms in a solid form a "matrix", and that the positions of the nuclei within that matrix remain relatively stable. The nuclei will vibrate due to thermal energy, but will generally maintain the same neighbors.

but why does the protons (and the object) goes towards the side of the negatively charged object as seen on the visualizations, if protons doesn't actually move?

Do not confuse visualizations of charge with the actual movement of charge. Visualizations of electric phenomena often show an accumulation of plus signs ("+") in some area. The accumulation of positive charge in an area is actually the result of electrons leaving that area. Similarly, visualizations of electric phenomena often show plus signs in motion. However, the motion of these plus signs actually represents the motion of electrons in the opposite direction. When an electron moves from a neutral area to a positive area, one of the "plus signs" disappears, but the previously neutral area became positive. So the net result is a "plus sign" appeared to move from one area to another. But (in a solid) this does not really represent the movement of positively charged particles, but the movement of electrons.

[In electrolytic solutions and plasmas, positively charged ions actually do move from place to place, but that is a different story.]

$\endgroup$
0
$\begingroup$

One way to think about it, is to introduce the idea of a "hole", which represents a place where an electron should be if the object were neutral. You can think of a hole as a kind of particle with positive charge. When people draw cartoons of static electricity, they often draw negative charges moving to one side of a surface and positive charges to the other. You are right that the protons don't as much as is shown in such cartoons. But, you can think of the positive charges they are drawing as being holes. The positively-charged holes show you where there is an underdensity of electrons in the material.

$\endgroup$
-1
$\begingroup$

The balloon is lighter than the stick, so the protons have to pull less mass than the electrons on the negatively charged stick. If they had to carry their own mass only, the electrons, if considered separate also, would travel more to the proton than the proton to the electron, wrt their center of mass. As you say. But inside matter they don't stand alone.

It's like you, if you were a very heavy person, connected with a rope to a very light person pulling the rope both. Normally the light person will move more to the center of mass. But when a heavy weight is attached to that light person and a small to you, the situation can be reversed.

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.