PHYSICS A2 UNIT 2 SECTION 1: RADIOACTIVITY & NUCLEAR ENERGY

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1 PHYSICS A2 UNIT 2 SECTION 1: RADIOACTIVITY & NUCLEAR ENERGY THE ATOMIC NUCLEUS / NUCLEAR RADIUS & DENSITY / PROPERTIES OF NUCLEAR RADIATION / INTENSITY & BACKGROUND RADIATION / EXPONENTIAL LAW OF DECAY / NUCLEAR DECAY / MASS DEFECT & BINDING ENERGY / NUCLEAR FISSION & FUSION / NUCLEAR FISSION REACTORS # Question THE ATOMIC NUCLEUS 1 What was the model for an atom at the start of the 20 th century? Whose was this model? 2 What was the method for Rutherford s experiment? 3 What did Rutherford expect with his experiment? 4 What were the actual results? Where did most of the particles go (and how many) Where did a small minority of the particles go (and how many) 5 What were the 3 conclusions from Rutherford s experiment? 6 Why is thin gold used in the experiment? 7 Why is a vacuumed chamber used? 8 Why do all the alpha particles in the beam have the same speed? 9 Why was the beam of alpha particles very thin? 9.1 Draw the alpha scattering of alpha particles fired at different angles to the gold particles 9.2 Through what angle is an alpha particle that bounces back deflected? 9.3 At the point where an alpha particle stops near a gold nucleus, what are it s energies? 9.4 How is the deflection of an alpha particle through 180 o an example of conservation of energy? 9.5 How can you use the conservation of energy of an alpha particle to predict the radius of the nucleus? 10 What do electrons act like in order to be diffracted? 11 What do electrons not interact with? 12 What is a de Broglie wavelength? 13 What is the equation for the de Broglie wavelength? 13.1 Why is an electron diffracted? 14 What does an electron diffraction pattern look like? 14.1 What is the equipment used for electron diffraction experiment? 14.2 What do the measurements show? 14.3 Why does scattering of the beam electrons occur? 14.4 Why does diffraction of the beam electrons occur? 15 What is the first minimum? 16 When does the first minimum appear? 17 How can measurements from the first minimum predict the radius of the nuclei? 18 What is the average size of the nucleus in the order of? 19 What is the size of the nucleus compared to the atom as a whole? 20 What happens to the size of the radius as the nucleon number increases? 21 What would a graph of radius of nucleus against nucleon number look like?

2 22 Under what conditions is a graph, which compares radius of nucleus and nucleon number, a straight line? 23 What equation would you use to calculate the radius of an atom from its nucleon number? 24 How does nuclear density differ for different elements? 25 What is the nuclear density compared to the atomic density? 25.1 What is the equation for finding nuclear density? 26 Hence, what 3 conclusions can be made about the structure of the atom? PROPERTIES OF NUCLEAR RADIATION 26.1 What is radioactive decay? 27 How would alpha, gamma and beta radiation be deflected in this magnetic field: 28 Complete this table about the three types of radioactive radiation: Radiation Symbol Constitution Relative Mass (u) Charge Alpha Beta-minus Beta-plus Gamma J 29 What is ionisation? 30 What is the range of ionisation? 31 What are the ionisation strength and ranges of: Alpha radiation Beta plus/minus Gamma rays 32 What is a cloud chamber? 33 What would the path of an alpha particle look like through a cloud chamber? Why? 34 What would the path of a beta particle look like through a cloud chamber? Why? 35 What would an absorption test look like with a Geiger-Müller tube? 36 How would a Geiger-Müller experiment measure the penetration of a radioactive source? 37 What are the ionising power, speed and penetrating power of the following types of radiation: Alpha Beta-minus Beta-plus Gamma 38 Why does the beta-plus particle have virtually zero charge? 39 What are some uses of: Alpha radiation Beta plus/minus Gamma rays INTENSITY & BACKGROUND RADIATION 40 What is the intensity of radiation? 40.1 Define intensity, I 41 What is the radiation energy per second from the source equal to? 42 What is the total area through which the radiation acts equal to? 43 Hence, what is the intensity of the radiation at any distance equal to?

3 44 What is the k constant? 45 What is the relationship between intensity of radiation and the distance from the source? 46 How can you experimentally test the relationship between intensity of radiation and the distance from the source? 47 What is background radiation? 48 How can you record and remove the effects of background radiation when reading from a radioactive source? 49 What are 5 sources of background radiation? 50 What is the nature of radioactive decay? 51 What are isotopes? 52 What is the rate of radioactive decay in the same isotopes? 53 What is the activity, A, of a radioactive source? 54 What is the unit of activity? 55 What is λ in radioactivity? 56 What is the unit of λ? 57 What are the two equations for finding the activity of a radioactive source? 58 What is the equation for the rate of change of the number of unstable nuclei? 59 What is the half-life of an isotope? 60 What is the equation for the number of nuclei remaining? 61 How does the number of unstable nuclei decrease with time? 62 What would a graph of number of unstable nuclei remaining against time look like? 63 How would you read the half-life from a graph of number of unstable nuclei against time? 64 How would you take the natural log of the equation for the number of nuclei remaining? 65 What would a graph of the natural log of the equation for the number of nuclei remaining look like? 66 What would the gradient of a graph of the natural log of the equation for the number of nuclei remaining represent? 67 How can the half-life be calculated from the decay constant? 68 What is the proof for the equation:!!/! =!"!! 69 What is a third equation for the activity of a source? 69.1 What is the energy transferred per second from a radioactive source equal to? 70 What are the dangers of ionising radiation? 71 What are the effects of ionising radiation on living cells? 72 How is 14 C made? 72.1 How are radioactive isotopes used in radiocarbon dating? 72.2 What equations are used in radiocarbon dating? 73 Why is it difficult to get a reliable age from radiocarbon dating? (5) 74 How can radioactive isotopes be used in medical diagnosis? 75 Why is Technetium-99m suitable for medical diagnosis? 75.1 How does Technetium-99m decay? 75.2 What does the m in Technetium-99m mean? 75.3 What precautions are taken with radioactive isotopes in medical diagnosis? 76 How can radioactive tracers be used in engine wear? 77 What is uranium-235 used for? 78 What are the problems with the storage of radioactive waste? 78.1 What are the kinetic energy spectra for alpha and beta decay? Hence what is alpha? NUCLEAR DECAY 79 Why may nuclei be unstable? 80 What is nuclide notation? 81 What is a stability graph?

4 82 Label this stability graph: 83 Where do light nuclei (with Z<20) sit on the stability graph? 83.1 What happens as Z & A increase beyond 20? 84 Where do alpha emitters sit on the stability graph and why? 85 Where do beta minus emitters sit on the stability graph and why? 86 Where do beta plus emitters sit on the stability graph and why? 86.1 Where does electron capture sit on the stability graph and why? 87 When does alpha emission happen? 88 What is the general equation for alpha decay? 89 When does beta minus emission happen? 90 What is the general equation for beta minus decay? 91 When does beta plus emission happen? 92 What is the general equation for beta plus decay? 93 When are electrons captured? 94 What is the equation for electron capture? 95 When are gamma rays emitted? 96 What changes in the emission of a gamma ray? 97 What are the N-Z changes for alpha, beta+ and beta- decay? MASS DEFECT AND BINDING ENERGY 98 What does! =!!! mean? 99 What happens when a particle and its antiparticle meet? 100 What is pair production? 101 What does! =!!! mean? 102 What happens to the energy in alpha decay? 103 What happens to the energy in beta decay? 104 What happens to the energy in electron capture? 105 What is the strength and range of the strong nuclear force? 106 Define the mass defect 107 What is the mass defect? 108 What is the equation for the mass defect? 109 What is binding energy? 110 Define binding energy? 110 What is the equation for the binding energy? 111 What is the comparative binding energy per mass defect for different nuclei? 112 What are the binding energies of each nuclide? 113 Define the binding energy per nucleon? 114 What is the binding energy per nucleon a measure of? 115 What is the equation for the binding energy per nucleon?

5 Draw and explain a graph of binding energy per nucleon against nucleon number, for all elements NUCLEAR FISSION AND FUSION What is nuclear fission? What does each fission event release? What happens to the binding energy per nucleon in nuclear fission? What is nuclear fusion? What happens to the binding energy per nucleon in nuclear fusion? When can nuclear fusion take place? What is released in nuclear fusion? What is the equation to work out energy released in nuclear fusion? How is solar energy produced? How can you tell if particles undergo fusion or fission from a graph of binding energy per nucleon against nucleon number? How can you estimate the average increase in binding energy per nucleon from the graph? NUCLEAR FISSION REACTORS Label this nuclear reactor: What does a thermal nuclear reactor contain? What is a pump used for in a nuclear reactor? What is a chain reaction in a nuclear reactor? What isotope? Chain reaction Thermal neutrons 132 How are the control rods altered to absorb more/fewer neutrons? What is a moderator in a nuclear reactor? 133 How can you choose a suitable moderator? 134 What is the critical mass in a nuclear reactor? 135 What are control rods? 136 Why is a coolant used in a nuclear reactor? 137 What are the safety features of a nuclear reactor? 1) Reactor shielding 2) Emergency shut-down 3) Fuel and disposal of fission waste products 138 How is high-level radioactive waste dealt with? 139 How is intermediate-level radioactive waste dealt with? 140 How is low-level radioactive waste dealt with?