1.5 Fundamental Particles and Exchange Particles

Question 1

What are the two largest forces acting on the particles in a nucleus?

Answer 1

The electromagnetic force (between protons) and the strong nuclear force.

Question 2

What is the range of repulsion of the strong nuclear force?

Answer 2

Between 0 and 0.5 fm

Question 3

What is the range of attraction of the strong nuclear force?

Answer 3

Between 0.5 and 3 fm

Question 4

Explain how we know that there must be a strong nuclear force.

Answer 4

The electrostatic force repulsion is much greater than the gravitational attraction. Without another force, the strong nuclear force, the nucleus would fly apart.

Question 5

What is an exchange particle?

Answer 5

A virtual particle that lets a force ac between two particles in an interaction.

Question 6

Name the electromagnetic force exchange particle.

Answer 6

Virtual photon

Question 7

Name two exchange particles of the weak interaction.

Answer 7

W⁺ and W^- bosons

Question 8

What do the straight lines on particle interaction diagrams represent?

Answer 8

Particles (not exchange particles)

Question 9

Why would a nucleus undergo electron capture?

Answer 9

Because it is proton rich

Question 10

What is the difference between electron capture and electron-proton collisions?

Answer 10

In electron capture, a proton in a nucleus captures an electron from the atom, turning into a neutron and emitting a neutrino.

In an electron-proton collision, a free electron collides with a free proton, producing a neutron and a neutrino.

Question 11

What is the exchange particle for electron capture, and what particles are produced?

Answer 11

W⁺ boson

Neutron and electron neutrino are produced