Why do quarks have fractional charges if charge is quantized?

[exec]

When I first study the chapter Charge, I was told that charges are quantized, that is, you can't find a charge of like 6.2e or 1/3e.

But later, when I got into the quantum theory, I was told that there are quarks, which have charges like +2/3e or -1/3e.

Don't these two statements contradict?

How can we explain this contradiction?

 

[cristo]

No, the two statements do not contradict one another. Any particle has a charge of an integer multiple of e. Particles, like the proton for example, are made up of a quarks, the sum of the charges of which will always equal an integer multiple of e-- in the case of a proton, +e.

 

[Mr Virtual]

I would like to add here that electric charges in the macroscopic world develop only due to exchange of electrons/protons. Though protons are made of quarks, these quarks never roam about freely to create any sort of charge or current in a body. So, we only consider the charge on an electron or a proton while studying electrostatics and electrodynamics, which ,as you know, always remains constant.

Mr V