# charge motion?

Discussion in 'Electronic Basics' started by Miscura, Feb 3, 2005.

1. ### MiscuraGuest

when a current is flowing trought a circuit the electric charge which
moves are only negative types or even positive charge move in the
opposite toward? in other words: positive charges are heaviest than
the negative charges, does this fact stop their moving? thanks

2. ### Bob MastaGuest

It's not the mass of the charges, it's that only electrons are mobile
in normal circuit materials like metals. The rest of the atom becomes
positive if an electron is missing, but there are still other electron

bonds holding it to surrounding atoms in the metal, so it can't move.
So only the negative electrons carry the current.

Ionized gasses are different, since the ionized atoms aren't bound
to neighbors and can move.

In semiconductors there can be a situation where there are missing
electrons in the crystal lattice. An electron can move from hole to
hole to provide a current flow, which can be regarded as if the
hole was moving in the opposite direction. So you get the
equivalent of a positive carrier flow, in a practical sense if not
in a literal sense.

Bob Masta