Flashcards
2022-02-10
Where is all radiation emitted from??
An unstable nucleus.
What are the four different types of radiation??
- Alpha
- Beta-minus
- Beta-plus
- Gamma
What particle is emitted in beta-minus radiation??
An electron.
What particle is emitted in beta-plus radiation??
A positron.
What instrument do you use to detect radiation??
A Geiger-Muller counter.
What must you subtract from every Geiger-Muller counter in order to accurately determine the radioactivity of a substance??
The background radiation.
What sort of things does the background radiation come from??
Earth, cosmic rays, food.
What is a cloud chamber used for??
Seeing the path that ionising radiation takes.
What does a Geiger counter not tell you??
The type of radiation.
How do you determine what type of radiation something is??
Look at how far it travels and what it passes through.
What particle mediates alpha radiation??
An alpha particle, $\alpha$
What happens to the number of protons and neutrons in the nucleus during alpha radiation??
- Protons: $-2$
- Neutrons: $-2$
How ionising is alpha radiation??
Strongly ionising.
Why is alpha radiation strongly ionising??
Because alpha particles have a large mass and charge.
What charge does alpha radiation transmit??
$$ +2e $$
What is the approximate mass of an alpha particle in atomic mass units $u$??
$$ 4u $$
How fast are the alpha particles in alpha radiation??
Slow.
Why are alpha particles slow??
Because they are heavy.
How far do alpha particles travel in air??
$$ \approx 5\text{cm} $$
What are alpha particles typically absorbed by??
Skin and paper.
What particle mediates beta-plus radiation??
A position, $\bar{e}$
What happens to the number of protons and neutrons in the nucleus during beta-plus radiation??
- Protons: $-1$
- Neutrons: $+1$
Why is the ionisation of beta-plus radiation typically glossed over??
Because the positron annihilates electrons.
What charge does beta-plus radiation transmit??
$$ +1e $$
What is the approximate mass of a beta-plus particle (a positron) in atomic mass units $u$??
$$ 1/2000 u $$
What is the typical speed of a beta-plus particle??
Fast.
Why are beta-plus particles fast??
Because they are very light.
Why don’t beta-plus particles travel very far??
They very quickly become annihilated.
What particle mediates beta-minus radiation??
An electron, $e$
What happens to the number of protons and neutrons in the nucleus during beta-minus radiation??
- Protons: $+1$
- Neutrons: $-1$
Relatively how ionising is beta-minus ionisation??
Moderately ionising.
What charge does beta-minus radiation transmit??
$$ -1e $$
What is the approximate mass of a beta-minus (an electron) particle in atomic mass units $u$??
$$ 1/2000 u $$
What is the typical speed of a beta-minus particle??
Fast.
Why are beta-minus particles fast??
Because they are very light.
How far do beta-minus particles travel in air??
$$ \approx 1\text{m} $$
What are beta-minus particles typically absorbed by??
$1-3\text{mm}$ of aluminium.
What mediates gamma radiation??
Photons.
What happens to the number of protons and neutrons in the nucleus during gamma radiation??
Nothing.
Relatively how ionising is gamma radiation??
Weakly ionising.
What charge does gamma radiation transmit??
$$ 0 $$
What is the speed of gamma ray radiation??
The speed of light.
What is gamma radiation typically absorbed by??
A few centimeters of lead or thick concrete.
2022-02-14
What order of magnitude is the speed of an alpha particle??
$$ 10^6 \text{ms}^{-1} $$
What order of magnitude is the speed of a beta-plus or beta-minus particle??
$$ 10^8 \text{ms}^{-1} $$
What does the setup for testing what type of radiation a radioactive source is emitting (ideally as a very poorly drawn diagram)??
How can you use this setup to test what type of radiation a source is emitting??
- Vary the distance of the Geiger-Muller tube.
- Place absorbers between the source and detector.
What distance do you have to place absorbers away when using this setup to ensure you account for all types of radiation??
$$ 5 \text{cm} $$
Why is it difficult to use this setup to determine the type of radiation something is by varying the distance between the source and detector??
Because it’s hard to ensure the radiation is travelling directly towards the tube.
What four things can you do to ensure safety when handling radioactive sources (MMHD)??
- Minimise exposure time
- Maximise distance to source
- Handle with tongs
- Don’t point at anyone
2022-02-17
Why does a beta-plus or a beta-minus get deflected more than an alpha particle in an electric or magnetic field despite having a smaller charge??
Because the mass is much smaller, its much easier for the force to change its motion.
What happens to a gamma ray in a magnetic or electric field??
Nothing; it’s not deflected at all.
What happens to a “parent nucleus” in nuclear decay??
It decays into a daughter nucleus.
What two quantities are always conserved in nuclear decay and nuclear decay equations??
Nucleon number and proton number.
Here is alpha decay of a mystery element $X$: $$^A_Z X \to ^{??}_{Z-2} Y + ^4_2 \text{He}$$ What is the missing value??
$$ A - 4 $$
Here is the beta-minus decay of a mystery element $X$: $$^A_Z X \to ^A_{??} Y + ^0_{-1}e + ^0_0 \bar{v_e}$$ What is the missing value??
$$ Z + 1 $$
Here is the beta-plus decay of a mystery element $X$: $$^A_Z X \to ^{??}{A - 1} Y + ^0{-1}e + ^0_0 \bar{v_e}$$ What is the missing value??
$$ A $$
Here is the gamma decay of a mystery element $X$: $$^A_Z X^{*} \to ^{??}_{Z} X + ^0_0 \gamma$$ What is the missing value??
$$ A $$
What does the fun asterisk $X^$ represent in the gamma decay equation $X$: $$^A_Z X^{} \to ^{??}_{Z} X + ^0_0 \gamma$$??
The fact the nucleus is excited.
When is gamma radiation normally emitted??
Alongside an alpha or beta radiation.
What type of radioactive nuclear decay doesn’t form a new element??
Gamma.
For light nuclei, what is typically true about the ratio of protons to neutrons??
It is roughly the same.
For heavy nuclei, what is typically true about the ratio of protons to neutrons??
There are more neutrons than protons.
What type of radiation is common for very heavy nuclei and why??
Alpha radiation, because the nuclei are trying to quickly reduce their mass.
What type of radiation is common for nuclei with too many protons??
Beta-plus.
What type of radiation is common for nuclei with too many neutrons??
Beta-minus.
What is “greatest number of ion pairs” overly complicated science talk for??
“most ionising”.
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date: 2022-02-10 17:42
tags:
- '@?public'
- '@?school'
- '@?physics'
- '@?a-level'
- '@?year-2'
- '@?radioactivity'
title: Physics - Radioactivity
