Sorry for the elementary question, but I have read several different answers and they disagree with each other (or are less than complete).

Why does the balloon stick to the wall?
I understand the balloon being negatively charged, but why would that cause it to stick to the neutral wall?
If something is neutral, then it would not be attracted to negatively, or positively charged matter, correct?
The one description I read, that seems to make most sense is that electrons are basically free to "move around" the proton, so when you bring the balloon close to the wall, the electrons in the wall are repelled to the "other side" of the proton exposing a positive surface to be attracted to the excessive electrons in the balloon.
Is this correct (or at least the popular view)?

If this is true, then would positively charged matter be attracted to neutral matter?
(due to attracting the electrons to the facing surface of the matter)

How (if at all) does this relate to the "levitation" effect of superconductors?

Thanks for indulging me and my stoopid questions. :)

hello one_raven.

When you blow up a balloon you inadvertantly rub it. This movement charges the balloon. Now even though the wall is Earthed and should not have any charge it does contain small amounts of water on it (from the air). The polar water molecules attracts the charged balloon.

Superconductors are not related to electrostatics.

Thanks for your reply.

Well, like I said, I understand that rubbing on the balloon would cause it to become negatively charged due to the transfer of electrons, but I don't get how condensation on the wall would cause it to attract the negatively charged balloon.

That doesn't add up for me.
Maybe I am missing something.

1.) Isn't the effect of static electricity and static cling more pronounced in a drier environment?
2.) Isn't water electrically neutral unless acted upon by an external force?

Take a look at these animations I came across...

Electrostatics (http://webphysics.davidson.edu/course_material/py230l_wc/demo/illustration22_4.html)

They are pretty, but are they accurate?

Is it that easy to polarize atoms?

Does it work both ways?
For example, like I said earlier, I read somewhere about the Electrons being relatively free to "move about", but, in these animations (specifically the one with the grounded plate) it seems just as easy for the Protons to move.
Or is it that electrons are drawn from the grounded plate, thereby causing the object to have a negative net charge?.

If the protons were able to move around (and even leave an object via the means of a grounded plate) wouldn't that have an effect on the mass and physical make-up of an object?

On the other hand...
If Electrons were "loose" and able to simply be shifted to the other side of an object that easily, but not Protons, wouldn't everything be electrically attracted to each other?
The Electrons of object A repelling the Electrons of object B, would polarize object B and cause the Protons of object B to be exposed with no electrons on the surface facing object A, which would in turn cause the + face of object B be attracted to the - face of object A which would then be oppositely polarized?
(sorry if that is not worded well)

I would appreciate it if someone gave me the key(s) to this that I am apparently missing.

A related question:
Is the force of attraction of unlike charges equal to the force of repulsion of like charges?

This thread has almost sixty views now and only one reply (other than mine)...
Are the questions that simple and stupid that no on wants to waste their time replying?:confused:

one_raven:

Let's say the balloon is negatively charged. The wall contains atoms which have positive and negative changes. When the balloon is brought near the wall, the negative electrons in the wall are pushed away from the negatively charged balloon, leaving a net positive change on the outer surface of the wall. This charge attracts the balloon charge and so the balloon sticks.

Note that this doesn't work if the wall is a conductor, since charge can then flow from the balloon to the wall.

<i>How (if at all) does this relate to the "levitation" effect of superconductors?</i>

It doesn't. The levitation effect is due to the superconductor excluding magnetic fields from its interior.

<i>1.) Isn't the effect of static electricity and static cling more pronounced in a drier environment?</i>

Yep, because water conducts a bit.

<i>2.) Isn't water electrically neutral unless acted upon by an external force?</i>

Water is always ionised a little.

<i>Is it that easy to polarize atoms?</i>

Yep.

<i>I read somewhere about the Electrons being relatively free to "move about", but, in these animations (specifically the one with the grounded plate) it seems just as easy for the Protons to move.</i>

In normal materials, it is usually the electrons which move. However, in an abstract sense, we talk about "charge" in the absence of specific particles. We often don't worry about what is the source of the charge. In many instances, the effect of negative charge moving from left to right, for example, is exactly equivalent to the effect of an equal amount of positive charge moving right to left.

<i>If Electrons were "loose" and able to simply be shifted to the other side of an object that easily, but not Protons, wouldn't everything be electrically attracted to each other?</i>

Only if there is a net charge.

<i>Is the force of attraction of unlike charges equal to the force of repulsion of like charges?</i>

Yes.

<i>Are the questions that simple and stupid that no on wants to waste their time replying?</i>

No.

Originally posted by James R
Let's say the balloon is negatively charged. The wall contains atoms which have positive and negative changes. When the balloon is brought near the wall, the negative electrons in the wall are pushed away from the negatively charged balloon, leaving a net positive change on the outer surface of the wall. This charge attracts the balloon charge and so the balloon sticks.


<i>Is it that easy to polarize atoms?</i>

Yep.

<i>Is the force of attraction of unlike charges equal to the force of repulsion of like charges?</i>

Yes.


Ok, this is where I got this question from:
If Electrons were "loose" and able to simply be shifted to the other side of an object that easily, but not Protons, wouldn't everything be electrically attracted to each other?

If electrons move about as freely as they do, then why aren't all electrically neutral objects electromagnetically attracted to each other at least on some level.
Take two neutral chunks of copper, for example.
As you move them closer together, the negative charge from the "surface" electrons from chunk A would repel the negative charge from the "surface" electrons from chunk B, right? (just like in the balloon example)
And, since matter polarizes so easily, the electrons from either chunk A or chunk B (let's say chunk B is slightly bigger) would be repelled, resulting in a polarized chunk of copper (A) with its positive surface facing the neutral face of the chunk B.
The positive surface of chunk A would attract the surface electrons of chunk B, thereby causing attraction between the two chunks.

I know there must be holes in this scenario, but can anyone tell me where they are?

Also...
Would positively charged matter be attracted to neutral matter the same way that negatively charged matter is?
Do you know of any way I can test this?

Thanks.

wouldn't everything be electrically attracted to each other?Only if they're very close. See Van der Waals forces (http://www.chemguide.co.uk/atoms/bonding/vdw.html)

Would positively charged matter be attracted to neutral matter the same way that negatively charged matter is?
Do you know of any way I can test this?Yes, and yes.
Rubbing different materials together will give different charges on each material. See the last link below for a table of materials.

Any charged material brought near a thin stream of water running from a tap will cause the stream to bend toward the charged object.


Here are some interesting sites:
http://www.geocities.com/CapeCanaveral/Launchpad/4586/basic16.html
http://www.uccs.edu/~tchriste/courses/PES100/100lectures/charge.html
http://www.acesinternational.org/Secrets%20&%20Tips%20Electronics2%20(pg.2).htm
http://stchs.org/science/courses/snc1dp/elect/elect1.htm

Thank you.
That was very helpful.

I read a few pages about Van Der Waals forces.
They all succintly describe the difference between Dipole-Dipole forces and Dispersion forces and what causes them.

What I can't find, however, is a measurement of how much force is exerted.
The sites that mention force simply discount it as "negligible".

Has it been measured?

I usually look Here (http://physics.nist.gov/cuu/Constants/index.html) but I don;t see it there either (unless, of course, it has another name that I am not aware of).

Any idea where to look?

Also, I am curious if they follow the inverse square law of electromagnetic and gravitational forces.

It seems that "London Forces" is a more specific name.

Try these:
http://www.pnas.org/cgi/content/full/99/19/12252 (about gecko's feet!)
http://www.pnas.org/cgi/content/full/99/19/12252 (this one seems good)
http://classes.engr.arizona.edu/mse110/announces2003/Lecture%20Slides/L10.pdf

Sorry I can't be more helpful - I'm an IT person, not a physics or chemistry guru.

Help the math impaired, please. :( .

The site says:
"While dipole-dipole, dipole induced-dipole and London forces are very weak around 1kJ/mole, the hydrogen bonds are fairly strong with 10 kJ/mol"

I wanted to somehow relate that in my mind to electromagnetic force and gravitational force.

Does it lie somewhere in the middle?

Gravity is 10^36 weaker than electromagntic force, and they abide by the inverse square law.

I still can't find any mention of whether or not the inverse square law applies to Van Der Waals forces.
Without knowing that, there is no way I can compare and contrast the forces, right?

Any help would be much appreciated.
In the mean time, I will keep searching.

It seems there are no Chemistry people around! (This is an area of Chemistry rather than physics)

I found something at http://www.everything2.com/index.pl?node=van%20der%20Waals%20forces

It seems that London forces are inversely proportional to the <i>seventh</i> power of the distance!
F_{induced dipole} = - constant × R^-7
The constant of proportionality depends on the molecules involved.

Simple answer:

The balloon induces a positive charge in the wall.

Wall normally:

+-
-+
+-
-+
+-
-+

Wall with balloon

-+ --
-+ --
-+ --
-+ --
-+ --

Easy as pie ;)

And also,

Balloon normally:

+-
-+
+-
-+
+-
-+

Balloon after rubbing:

-+
-+
-+
-+
-+
-+

as he said, easy as pie!!!