Earth's Gravitational and Magnetic Fields
Most recent answer: 04/17/2013
- EB (age 17)
Augusta,GA, USA
We've answered most of your questions in various threads on this site, i.e. . Search around for the long answer.
Here's the short answer: electromagnetism is strong enough on a short range that atoms are very stable when arranged in a crystal or other dense structure. The details within a specific structure are complicated, but in general it is the attractive forces between opposite charges which hold together molecules and atoms.
On a small scale, these forces are significant. The forces fall off very rapidly over a long scale, however, since positive and negative charges mostly cancel each other out. So, electricity and magnetism become weak very rapidly for large-scale phenomena (like the earth's fields).
Gravity is a completely different force. In addition, there are no "negative mass" objects to provide repelling forces with gravity, so gravity doesn't cancel out over long distances. This is why the earth's gravity is important, but it's electromagnetic fields are less so.
David Schmid
(published on 04/17/2013)