AQA AS Level Physics Paper 2, June 2023: Question 23

1 mark · Medium difficulty · Multiple Choice

Identify the property required for exchange particles when explaining forces between elementary particles.

Practise this question

Question

Multiple choice question 23 asks which property exchange particles must have, with four options: A charge, B momentum, C phase, and D rest mass.
Question text

23 The concept of exchange particles was introduced to explain forces between elementary

particles.

This concept requires that exchange particles have

[1 mark]

A charge.

B momentum.

C phase.

D rest mass.

Mark scheme

Show the mark scheme The mark scheme indicates that the correct answer for question 23 is option B, momentum.

23 B momentum

How to answer it

Properties of Exchange Particles

What this question tests

This question assesses your fundamental understanding of particle interactions and the properties that exchange particles (virtual particles) must possess to facilitate forces between elementary particles according to quantum field theory.

Question 2.3

Properties required by exchange particles

✅ Correct Answer

B: momentum

Exchange particles must transfer momentum between particles when they are emitted and absorbed, which is precisely how repulsive and attractive forces are generated at a quantum level.

💡 Key Knowledge

  • Momentum transfer: For a force to act between two bodies, momentum must be exchanged (as dictated by Newton's laws and conservation of momentum).
  • Virtual particles: Exchange particles exist temporarily to mediate the fundamental forces (electromagnetic, weak, strong, and gravitational).

🧠 Exam Technique

In multiple-choice questions involving definitions, eliminate options that are not universally true for all exchange particles:

  • Not all exchange particles have charge (e.g., gravitons, Z⁰ bosons, and some gluons are neutral).
  • Exchange particles do not require fixed rest mass or phase characteristics to mediate a force.

❌ Common Errors

Students frequently select A (charge) because they associate exchange particles primarily with the electromagnetic force (where photons carry electromagnetic force between charged particles). However, the strong and weak nuclear forces can involve neutral exchange particles (like the Z⁰ or neutral pions), meaning charge is not a universal requirement—whereas momentum transfer is fundamental to generating any force.

Mark Allocation: [1 mark] awarded for selecting option B.

Topics

Physics · 3.2 Particles and radiation

Question and mark scheme from the AQA AS Level Physics examination, Paper 2, June 2023. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.