Particle interactions Flashcards – AQA A-level Physics (7408)

What are the four fundamental interactions?

Gravitational, electromagnetic, weak nuclear and strong nuclear.

Between what does gravity act?

Masses.

Between what does the electromagnetic interaction act?

Electrically charged particles.

What decay process is caused by the weak interaction?

Beta decay.

What does the strong interaction, or strong nuclear force, bind together?

The constituents of atomic nuclei.

How can an interaction between elementary particles be represented?

As the exchange of a particle, providing a model for the force between them.

What does it mean for an exchange particle to be virtual?

It is internal to the interaction, not an incoming or outgoing particle detected independently.

What is the exchange particle in the electromagnetic interaction?

A virtual photon.

What does an exchange particle transfer between interacting particles?

Energy and momentum.

Which fundamental interaction governs beta-minus and beta-plus decay?

The weak interaction.

What are the two stages of beta-minus decay?

$n \rightarrow p + W^-$ followed by $W^- \rightarrow e^- + \bar{\nu}_e$.

What are the two stages of beta-plus decay?

$p \rightarrow n + W^+$ followed by $W^+ \rightarrow e^+ + \nu_e$.

What kind of particles are the $W$ particles in beta decay?

Virtual exchange particles.

What is conserved at each stage of beta decay?

Electric charge.

What happens in electron capture?

A proton in a nucleus interacts with an electron captured from an atomic shell, becoming a neutron and producing an electron neutrino.

What particle transformation can occur in an electron–proton collision?

$e^- + p \rightarrow n + \nu_e$

How can electron–proton conversion be represented using a virtual $W^-$?

The electron emits a virtual $W^-$ and becomes a neutrino; the proton absorbs it and becomes a neutron.

How can electron–proton conversion be represented using a virtual $W^+$?

The proton emits a virtual $W^+$ and becomes a neutron; the electron absorbs it and becomes a neutrino.