particles and radiation

• In what AQA A-level physics topic can the properties of particles be found?

  Particles and radiation
• What will students be able to do if they are successful in the lesson?

  Describe, list and convert particle properties
• The lesson links into which part of the AQA A-level physics specification?

  Constituents of the atom
• How can any particle in the universe be described?

  • Energy
  • Mass
  • Charge
  • Spin
  • Strangeness
  • Lepton number
  • Baryon number
• Which two particle properties are students likely to have encountered at GCSE level?

  Charge and energy/mass
• Which of the listed properties of particles is covered at degree level only?

  Spin
• What are the different descriptors that can be used to differentiate between different particles?

  • Energy and mass
  • Charge
  • Specific charge
  • Baryon number
  • Lepton number
  • Spin
  • Strangeness
• What is the mass of a proton?

  1.67 x 10^-27 kg
• What is the charge of a proton?

  1.60 x 10^-19 C
• What is the specific charge of a proton?

  9.57 x 10^7 C/kg
• What is the baryon number of a proton?

  1
• What is the lepton number of a proton?

  0
• What is the spin of a proton?

  1/2
• What is the strangeness of a proton?

  0
• Why is the kilogram not the most convenient unit for measuring particle masses?

  Particle masses are very small
• What equation is used to derive a more workable unit for particle masses?

  Mass-energy equivalence equation
• What is the most commonly used unit of mass by particle physicists?

  MeV/c^2
• Why is MeV/c^2 a useful unit for particle physicists?

  It gives a workable number
• What must be done to MeV/c^2 to determine its value in SI units?

  Convert back to kilograms
• According to $E=$$mc^2$, what is mass equal to?


  Energy over the speed of light squared
• How many joules are in one MeV?

  1.6 x 10^-13 J
• What is the value of c, the speed of light, used in the calculation?

  3 x 10^8 m/s
• What is the conversion factor between MeV/c^2 and kilograms?

  1 MeV/c^2 = 1.78 x 10^-30 kg
• What other unit of mass is used by particle physicists, especially in GCSE?

  Unified atomic mass unit
• What is approximately the mass of one unified atomic mass unit?

  Mass of one nucleon
• How is one unified atomic mass unit defined?

  1/12 of the mass of carbon-12
• What is the value of one unified atomic mass unit (u) in kilograms?

  1.661 x 10^-27 kg
• What must be done to convert from non-SI units (MeV/c^2 and u) into SI units (kilograms)?

  Multiply by the conversion factor
• Convert 17 MeV/c^2 into kilograms.

  3.03 x 10^-29 kg
• Convert 4 u into kilograms.

  6.644 x 10^-27 kg
• What are MeV/c^2 units of when using $E=$$mc^2$?


  Mass
• What are 'u' a simplified unit of?

  Mass
• What must be done to convert from SI units (kilograms) into non-SI units (MeV/c^2 and u)?

  Divide by the conversion factor
• Convert 2 x 10^-29 kilograms into MeV/c^2.


  11.2 MeV/c^2
• Convert 4 x 10^-27 kilograms into u.

  24.1 u
• In terms of charge, how were particles described at GCSE?

  Positive, neutral, or negative
• Why is the GCSE description of charge an approximation?

  Because charge must be in units
• In what units must we express charge?

  Coulombs
• What is the value of one unit of relative charge in Coulombs?

  1.60 x 10^-19 C
• What is the charge of an electron in coulombs?

  -1.60 x 10^-19 C