# Are the planets uncharged?

1. Jun 13, 2012

### Amrutha.phy

Planets are said to be uncharged... Leave about the rest but we consider earth as a negative potential (I suppose)... :tongue2: plz clarify my doubt...

2. Jun 13, 2012

### mathman

The earth is electrically neutral - I don't understand your question.

3. Jun 13, 2012

### HallsofIvy

Staff Emeritus
Where did you hear this?

I wonder if you aren't confusing gravitational potential energy with electric charge. Since potential energy is always relative to some fixed value, we are free to take it zero at any point. Because graviational force varies as $1/r^2$, gravitational potential varies as $1/r$ and it is simplest to take the zero point at infinity. And since gravitational potential decreases as you approach the earth, taking zero at infinity means the gravitational potential at any finite distance is negative.

However, that has nothing at all to do with "charge".

4. Jun 13, 2012

### hms.tech

building on from "hallsofivy's" comment, even if u consider the electrical approach ie using coulomb's law, the earth as a whole is considered to be at a zero potential,(in terms of charge) ie earth is neither positively charged nor negatively charged.

Hope that clears things up
Using the premise, the earth is neutral.

5. Jun 14, 2012

### Amrutha.phy

Yeah I confused between gravitational potential and charge... Yeah I got it clarified thank u..