Exchange Particles and Electromagnetic Force

Question 1

How do particles interact?

Answer 1

an exchange particle has to be passed between them

exchange particles are responsible for forces

they exert an equal and opposite force on each other and momentum is transferred ( boat diagram)

«<0-0»» (repulsion)

known as force carriers

Question 2

What is the name of exchange particles?

Answer 2

bosons

e.g. photons

Question 3

What is EM force responsible for?

Answer 3

reactions between charged particles

Question 4

What is the exchange particle for EM force?

Answer 4

photon, γ

Question 5

What causes beta decay and what is the exchange particle for it?

Answer 5

weak nuclear force

the w boson

Question 6

Compare the properties of the w boson and photon?

Answer 6

w boson has a charge (+ or -), photon has none

photon has no mass, w boson has a non-zero mass

w boson has a short range of 0.001fm and the photon has an infinite range

Question 7

What are the products of beta-minus decay

Answer 7

baryon -> anti lepton + lepton + baryon

e.g.

neutron -> anti-electron-neutrino + electron + proton

charge is balanced and so is mass

w- exchange particle

Question 8

What is b+ decay

Answer 8

proton-> neutrino + positron + neutron

Question 9

What is momentum?

Answer 9

mass x velocity

Question 10

Why are photons described by Feynman as virtual?

Answer 10

they cannot be directly detected

if we intercepted them it would stop the force acting

Question 11

What happens in a proton-antineutrino/neutron-neutrino interaction?

Answer 11

p-v:
- w+ exchange particle
- positron and neutron released
   _
n-v(bar):
- w- exchange particle
- electron and proton released

Question 12

What is electron capture?

Answer 12

atomic electron interacts w/ a proton in the nucleus via weak interaction

neutron formed, u quark changes to a down quark

electron neutrino released

w+ exchange particle