Free electrons attracted by Earth's gravity Free electrons in a metal are attracted by gravity towards Earth. So why don't they lay down to the bottom of the conduit, like sediment at the bottom of a river?
 A: Electrons have a negative electric charge, which means they repel other negative charges. Once electrons start to fall to the bottom of the conductor, there will be a greater accumulation of negative charges at the bottom of the conductor than the top. The accumulation of negative charges at the bottom will repel the other free electrons above them, stopping any further accumulation. Because the electric force is so much stronger than gravity, it takes very little movement of electrons to stop any further settlement. So little, in fact, that the difference in the density of electrons between the top and bottom of a conductor is undetectable.
A: This is because the gravitational force acting on electrons is significantly weaker than the electric forces that keep them attached to nuclei in atoms.
In fact, the ratio of the electrostatic force to the gravitational force between a proton and an electron works out to be $$\frac{F_e}{F_G}= {\large\frac{k\frac{q_e q_p}{r^2}}{ \frac{Gm_em_p}{r^2}}}= \frac{kq_e^2}{Gm_e m_p}\approx  2.27\times 10^{39}$$
meaning the electric force is about $10^{39}\times$ stronger than
the gravitational force.
This means that electric forces will keep the electrons from "falling" anywhere.
