A Level Physics Practice Exam

What quarks make up a pion?

1. Up, Up

2. Down, Down

3. Up, Anti-Down

4. Neutron and Proton

The correct answer is: Up, Anti-Down

Pions are mesons, which are a type of hadron composed of a quark and an antiquark pair. The specific combination of quarks in a pion is crucial to understanding its properties. A positively charged pion, commonly represented as \( \pi^+ \), consists of an up quark and an anti-down quark. This quark composition contributes to the pion's charge and allows it to participate in strong interactions. The presence of the anti-down quark alongside the up quark is what makes the total charge of the \( \pi^+ \) equal to +1, since the up quark carries a charge of \( +\frac{2}{3} \) and the anti-down quark carries a charge of \( +\frac{1}{3} \). The other types of pions include the negatively charged pion \( \pi^- \) which is made up of a down quark and an anti-up quark, and the neutral pion \( \pi^0 \) which is a mixture of up-antiup and down-antidown pairs. This distinction is key to understanding mesonic particles and their interactions within the framework of particle physics. Other combinations given in the options do not conform to