A-level Physics (Advancing Physics)/Quarks/Worked Solutions

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1. The Δ++ baryon is made up of up quarks. What is its total charge?

Baryons are made of three quarks. 3 x +⅔ = +2e

2. The Δ- baryon has a total charge of -1e. Given that it is made up of only one type of first generation quark, what is this quark?

Three identical quarks must have a total charge of -1e, so one of these quarks has a charge of -⅓e. This is a down quark.

3. What is an antiproton made of? What is its charge?

\bar{u}\bar{u}\bar{d}, total charge -1e.

4. A K+ meson is made of an up quark and an antistrange quark. What is its total charge?

⅔ + ⅓ = +1e

5. Lambda (Λ) baryons are made up of an up quark, a down quark, and another quark (not an antiquark). The Λ0 is neutral, and contains a second generation quark. What is this quark?

0 = +⅔ - ⅓ + q

q = -⅓

The second generation quark with a charge of -⅓e is the strange quark.