Pmt flash cards

• What does electromotive force (emf) represent in a circuit?

  It is the work done by an energy source in driving charge around the entire circuit, per unit charge.
• What is the main difference between emf and potential difference (pd)?

  Emf is the work done by an energy source in driving charge around the circuit, while pd is the work done transferring charge between two points.
• What does internal resistance refer to?

  It is the resistance within a power source due to its materials and components.
• How does internal resistance affect terminal potential difference?

  The larger the internal resistance, the smaller the terminal potential difference.
• What are 'lost volts' in a circuit?

  'Lost volts' refer to the difference in voltage between that supplied by the source and the amount available to the circuit due to internal resistance.
• What is the equation for lost volts?

  Lost volts = Ir
• What is the equation that relates emf to load and internal resistance?

  ε = I(R + r)
• What does Kirchhoff’s first law state?

  The total current going into a junction is equal to the total current leaving the junction.
• What is Kirchhoff's second law?

  For any path (loop) of a circuit, the sum of all potential differences must equal the total emf of the circuit.
• What is the evidence provided by the alpha-scattering experiment regarding the nucleus?

  A few alpha particles bounce back, indicating a small and dense nucleus.
• Why would alpha particles bouncing back suggest a dense positive charge?

  Because if the positive charge was evenly distributed, most alpha particles would pass through.
• What is an alpha (𝛂) particle?

  An alpha particle is a fast-moving Helium 2+ ion consisting of 2 protons and 2 neutrons.
• What are beta (𝛃) particles?

  Beta particles include fast-moving electrons (𝛃-) and positrons (𝛃+), both with negligible mass.
• What are gamma (𝛄) rays?

  Gamma rays are short wavelength, high energy electromagnetic radiation with zero mass and zero charge.
• Order Alpha, Gamma, and Beta radiation starting with the most ionising.

  • Alpha
  • Beta
  • Gamma
• Which type of radiation can only be stopped by a thick block of lead or concrete?

  Gamma radiation.
• How far does a beta particle typically penetrate in air?

  50 cm - 1 m.
• What are the nucleon and atomic numbers of a particle with nucleon number A and atomic number Z after alpha decay?

  Nucleon number = A - 4, Atomic number = Z - 2.
• In beta plus decay, how does the atomic number change?

  It decreases, as a proton turns into a neutron and a positron.
• Why does beta plus decay have very low penetration?

  Because positrons are annihilated by electrons almost immediately.
• How can electrons and positrons be described relative to one another?

  Electrons and positrons are antiparticles of each other.
• How does the atomic number change in beta plus decay?

  It decreases.
• Why does beta plus decay have a very low penetration?

  The positrons will be annihilated by electrons almost immediately.
• What is a difference and a similarity between particles and their antiparticles?

  They have a similar mass but opposite charges.
• Why do electrons/positrons emitted in beta decay possess a continuous range of emitted energies?

  Energy is shared between the electron and anti-neutrino or positron and neutrino.
• What are the six types of quark?

  Up (u), Down (d), Strange (s), Charm (c), Top (t), Bottom (b).
• What is the quark composition of protons?

  Two up quarks and one down quark.
• What is the quark composition of neutrons?

  One up quark and two down quarks.
• What is a hadron?

  A hadron is a sub-atomic particle comprising two or more quarks.
• What are the main classes of hadron?

  Baryons (three quarks) and Mesons (one quark and one anti-quark).
• Give two examples of baryons.

  Protons and neutrons.
• What are leptons?

  Leptons are fundamental particles not subject to the strong nuclear force.
• Give some examples of leptons.

  Electrons, Muons, Neutrinos, and their corresponding antiparticles.
• What are the charges of the up, down, and strange quarks?

  Up = +⅔e, Down = -⅓e, Strange = -⅓e.
• What is meant by beta minus decay?

  When a neutron turns into a proton and releases an electron and an anti-electron neutrino.
• Which quark decays in beta minus decay and what does it turn into?

  A down quark turns into an up quark.
• Which quark decays in beta plus decay and what does it turn into?

  An up quark is converted to a down quark.
• What quantities must be conserved during the decay of particles?

  Charge, mass, baryon and lepton numbers.
• What are the defining features of radioactive decay?

  Radioactive decay is spontaneous and random.
• What features of a nucleus might cause it to radioactively decay?

  Too many or too few neutrons, too heavy, or too much energy.