# Physics - Nuclear Physics > Source: https://ollybritton.com/notes/a-level/physics/topics/nuclear-physics/ · Updated: 2025-04-23 · Tags: school, physics, year-2 ## Flashcards ### 2022-03-28 ##### How can you calculate the energy of the two identical gamma photons released in the annihilation of an electron and positron pair?? Use $E = mc^2$ ##### How can you calculate the mass of the electron and positron created when two high-energy gamma photons collide?? Use $E = mc^2$ ##### What is pair production?? The creation of a particle and an antiparticle due to two high-energy gamma photons colliding. ##### How can you calculate the energy released in radioactive decay?? Convert the change in mass to energy using $E = mc^2$ ##### What is binding energy?? The minimum amount of energy required to separate a nucleus into its constituent parts. ##### What is the mass defect of a nucleus?? The difference in mass between the mass of the nucleus and the mass of the separate nucleons. ##### Which is heavier: the mass of a neutron or the mass of the constituent nucleons?? The mass of the constituent nucleons. ##### Why is the mass of the constituent nucleons of a nucleus heavier than the nucleus itself?? Because the binding energy is converted into mass. ##### Can you visualise the graph of binding energy per nucleon?? ![PHOTO BINDING ENERGY PER NUCLEON](binding-energy-per-nucleon.png) ##### ![PHOTO BINDING ENERGY PER NUCLEON](binding-energy-per-nucleon.png) Why does fusion stop at iron?? Because fusing iron into a new, heavier element will mean you lose energy. ##### What's an example of a process that creates energy from mass?? Annihilation. ##### Why is iron the most stable element?? Because it has the highest binding energy per nucleon. ##### What is the binding energy of a hydrogen nucleus?? $$ 0J $$ ##### What happens during induced fusion?? A nucleus absorbs a neutron and splits into two approximately equal nuclei and a few fast moving neutrons. ##### What's the fancy name for a slow-moving neutron?? A thermal neutron. ##### Why is it important to have slow-moving ("thermal") neutrons opposed to fast moving ones in the fission reaction for uranium-235?? Because the chance of decay is greater. ##### How can you calculate the energy released in a nuclear reaction using mass?? Convert the change in mass to energy using $E = mc^2$. ##### What is always true about the mass of a parent nucleus compared to the daughter nuclei in a nuclear reaction?? It is greater. ##### If you're not given the mass but instead the binding energy for a nuclear reaction, how can you work out the total energy released?? Work out the difference. ##### What is the purpose of a moderator in a nuclear reaction?? To slow down the neutrons. ##### In a stable reactor, what should be true about one nuclear reaction?? It leads to just one other nuclear reaction. ##### In what sense is a fission reaction a chain reaction?? The neutrons released can trigger further fission reactions. ##### What are the fuel rods made out of in a nuclear reactor?? Enriched uranium. ##### What is the purpose of the control rods in a nuclear reactor?? To slow down the rate of a nuclear reaction by absorbing neutrons.##### In what sense is a fission reaction a chain reaction?? The neutrons released can trigger further fission reactions. ##### What are the fuel rods made out of in a nuclear reactor?? Enriched uranium. ##### What is the purpose of the control rods in a nuclear reactor?? To slow down the rate of a nuclear reaction by absorbing neutrons. The neutrons released can trigger further fission reactions. ##### ![PHOTO NUCLEAR REACTOR](nuclear-reactor.png) Why would it be bad if the moderator water boiled?? Because then it wouldn't be as good at slowing down neutrons. ### 2022-03-31 ##### What is the general principle of fusion?? Forcing light nuclei together until the strong nuclear force takes over. ##### ${}^2_1 H + {}^1_1 p$ What would this fusion reaction make?? $$ {}^3_2 \text{He} $$ ##### What is true about the total binding energy after a fusion reaction?? It is larger, and the energy is released. ##### What is true about about the total mass after a fusion reaction?? It is smaller. ##### Above what element do you have to put more energy into a nuclear reaction than you get out of it?? Iron. ### 2022-06-04 ##### Why is a high speed proton needed in fusion reactions?? Because the proton will be repelled by the nucleus, so energy is needed to overcome this. ### 2022-06-05 ##### What is induced nuclear fission?? The splitting of a nucleus as a neutron is absorbed. --- Olly Britton — https://ollybritton.com. Machine-readable index: https://ollybritton.com/llms.txt