# Limit to charge density?

1. Feb 4, 2012

### kahwawashay1

We are doing electricity now in school and it made me wonder..
When there is too much mass in a certain amount of volume, it supposedly forms a black hole, right? Well, does anything happen when there is too much charge density?

I know this excess charge would want to neutralize itself and so it would pull on surrounding opposite charges, but lets say that its in a vacuum and so cannot neutralize itself

Also, on a related note, I find it fascinating that the electricity equations very much resemble gravitational equations...is there a simple explanation as to why this is so?

2. Feb 4, 2012

### mathman

Inverse square law.

3. Feb 4, 2012

### kahwawashay1

thanks.
does anyone know the answer to my first question though?

4. Feb 4, 2012

### Bobbywhy

kahwawashay1, Black hole formation is quite different from electrostatics. Trying to compare mass density and charge density is of limited value.

When there is large buildup of charge (voltage), or “too much charge density” a spark will try to jump or “arc” across a gap to discharge it. Natural lightning is a good example of this.

Here are two sources of information on charge density:
http://en.wikipedia.org/wiki/Charge_density
http://physics.bu.edu/~duffy/semester2/c03_chargedensity.html

Here is an example of a high voltage generator that creates a large charge density:
http://en.wikipedia.org/wiki/Van_de_Graaff_generator

When higher charge densities (voltages) are desired, for particle accelerators, for example, the charge generator can be placed in a vacuum. Another method is to pressurize the generator in a dielectric (insulating) gas:
http://en.wikipedia.org/wiki/Sulfur_hexafluoride