3.2.1.4 Particle interactions Flashcards
(21 cards)
What are the four fundamental interactions?
Gravity electromagnetic weak nuclear strong nuclear
What does the strong nuclear force do?
Holds protons and neutrons together in the nucleus
What does the weak nuclear force do?
Responsible for beta decay and other processes involving change in quark type
What does the electromagnetic force do?
Acts between charged particles
What does gravity do?
Acts between masses and is always attractive
What is the exchange particle for the electromagnetic force?
Virtual photon
What are the exchange particles for the weak nuclear force?
W+ and W- bosons
What is the concept of exchange particles?
Forces are mediated by particles exchanged between interacting particles
What is the range of the weak nuclear force?
Very short range about 0.001 femtometres
What is the range of the electromagnetic force?
Infinite
What is the range of the strong nuclear force?
Attractive up to about 3 femtometres repulsive below about 0.5 femtometres
What happens in beta minus decay?
A neutron changes into a proton emitting an electron and an antineutrino
What exchange particle is involved in beta minus decay?
W- boson
What happens in beta plus decay?
A proton changes into a neutron emitting a positron and a neutrino
What exchange particle is involved in beta plus decay?
W+ boson
What happens in electron capture?
A proton in the nucleus captures an orbiting electron and becomes a neutron emitting a neutrino
What exchange particle is involved in electron capture?
W+ boson
What happens in an electron proton collision?
An electron and a proton interact via the weak force producing a neutron and a neutrino
What exchange particle is involved in an electron proton collision?
W- boson
Why must exchange particles be virtual?
Because they exist only temporarily to transfer force and conserve energy momentum and charge
How can interactions be represented?
By simple diagrams showing incoming and outgoing particles and exchange particles between them
