Particles

• Define isotope.

  Different isotopes of an element have the same number of protons but a different number of neutrons.
• How do you calculate the specific charge of a particle?

  Specific charge = charge / mass
• What is the value of h (The Planck constant)

  6.63×10^-34 Js
• Complete:

  Every particle has a corresponding anti-particle. The anti-particle has the same mass as the particle but has the opposite value for charge.
• Explain annihilation

  If a particle meets its own anti-particle the two will annihilate. All the mass will be converted to photons of energy. Two photons must be created travelling in opposite directions so that momentum is conserved
• Explain pair production

  ONE photon with sufficient energy may provide the mass to produce a particle - anti-particle pair.
• Explain what the strong nuclear force is

  This force is what holds together the nucleons (protons and neutrons) that make up a nucleus. It also holds together the quarks inside each proton and neutron. It has to overcome the electromagnetic repulsion between protons so it's strongly attractive for normal separations of nucleons (a few fentometres). If nucleons get too close (<0.5fm) the strong force becomes repulsive since otherwise the nucleus would collapse inwards.
• The strong interaction is

  Attractive for separations between 0.5 fm and 3 fm
• The strong interaction is

  Repulsive for separations less than 0.5 fm
• The strong interaction is

  Zero for separations greater than 3 fm
• What is the weak nuclear force responsible for?

  Beta decay
• When does beta decay occur?

  When one type of quark changes into a different type of quark
• Which particles does the weak force affect?

  All particles, including both hadron and leptons.
• What is the only force that affects neutrinos?

  The weak force
• What does an alpha particle consist of?

  Two protons and two neutrons.
• What are two classifications of particles?

  Hadrons and leptons
• What are the two sorts of hadron?

  Baryons and mesons.
• What are some examples of leptons?

  Electrons, muons, neutrinos
• What are some examples of baryons?

  Protons, neutrons
• What are some examples of mesons?

  Pion, kaon
• True or false : Leptons are fundamental particles

  True
• Complete

  Protons and neutrons are baryons so they have a baryon number of +1
• Complete

  Anti-protons and anti-neutrinos are anti-baryons so they have a baryon number of -1
• Complete

  Mesons aren't baryons at all so they have a baryon number of 0
• Complete

  An electron is a lepton so it has a lepton number of +1
• Complete

  A neutrino is a lepton so it has a lepton number of +1
• Complete

  A positron (anti-electron) is an anti-lepton so it has a lepton number of -1
• Complete

  An anti-neutrino is an anti-lepton so it has a lepton number of -1
• Complete


  Protons and neutrons aren't leptons at all so they have a lepton number of 0
• What is always conserved when particles interact?

  Charge, baryon number and lepton number
• What are the only particles that experience the strong force?

  Hadrons - they are made of quarks and anti-quarks. They are baryons or mesons.
• What distinguishes hadrons from other particles?


  Experiencing the strong nuclear force
• What do baryons consist of?

  Three quarks
• What do mesons consist of?

  A quark and an anti-quark
• What do anti-baryons consist of?

  Three anti-quarks
• What is the baryon number of a quark?

  +1/3
• What is the baryon number of an anti-quark?

  -1/3
• What is the quark composition of a proton?

  UUD
• What is the quark composition of a neutron?

  UDD
• What is the only stable baryon?

  Proton