Physics - Nuclear Physics
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?
Why does fusion stop at iron?
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?
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.
Why would it be bad if the moderator water boiled?
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.