• Question: What is the charge of an up quark and the charge of a down quark? How many quarks make up a proton and a neutron?

    Asked by sammieblues to David, Luna, Mark, Melanie, Probash on 22 Mar 2011 in Categories: .
    • Photo: David Pyle

      David Pyle answered on 21 Mar 2011:

      Not my field.. Up quarks have a charge of +2/3, down have a charge of -1/3. To make a proton, take two ‘ups’ and a ‘down’ to get a charge of +1 (3 quarks). To make a neutron, take one up and two down – so three quarks, and zero charge.

    • Photo: Melanie Stefan

      Melanie Stefan answered on 22 Mar 2011:

      An up quark is thought to have a charge of +2/3 e and a down quark of -1/3 e. (Where e is the elementary charge, for instance electrons have charge -1e an protons +1e)

      A proton consists of two up quarks and one down quark, giving it a charge of (2*2/3-1/3)e = +1e

      A neutron is made up of one up quark and two down quarks, so its charge is (2/3-2*1/3)e = 0.

    • Photo: Luna Munoz

      Luna Munoz answered on 22 Mar 2011:

      I found the question (and answer) here. It’s a website with a .org so should be reputable. Perhaps one of the other scientists knows quantum physics a little better than me.

Comments