Fractional electric charge?

1. Jun 25, 2010

PrincePhoenix

According to the third paragraph over here,

"Quarks have the unusual characteristic of having a fractional electric charge, unlike the proton and electron, which have integer charges of +1 and -1 respectively."

What does the fractional electric charge mean? Which units are we talking about?

2. Jun 25, 2010

kaksmet

Fractional electric charge mean that the charge is not an integer, i.e. it is not something like 0, +1, -1, +2, -2... but instead something like 1/2 or 2/3.

In this case the unit is the electric charge of the electron. Most particles have an electric charge which is a multiple of the electron charge. Actually, all detected particles except for the quarks.
The quarks come in two types, with charge -1/3 and +2/3 and the anti-quarks have a charge of +1/3 and -2/3.

3. Jun 26, 2010

PrincePhoenix

Thanks. That cleared it up.