Physics - Radiation

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What is radiation?
Parts of atoms that are given off by radioactive atoms
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Some isotopes have an unstable nucleus so to become stable they give out ___
Radiation
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radioactive decay is a r__ process
random
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Undergoing radioactive decay is when...
unstable Atoms give out (emits) radiation from nucleus (e.g alpha/bata)
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Activity is the rate that an unstable nucleus ___
Decays
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It's measure in...
Becquerel (Bq)
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1 Bq = _ decay per second
1
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An alpha particle is the same as a __ particle
Heluim
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Why?
It has 2 protons and 2 neutrons
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What is a beta particle?
Electron that's shot from nucleus at high speed
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How are beta particles made?
Beta particles are formed in nucleus when a neutron changes into protons and an electron. Th electron is rejected and shot out of nucleus
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Are gamma rays particles?
No
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What are they?
They're type of electromagnetic radiation from nucleus
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Why can't scientists work out when a nucleus will decay?
Because it's a random process
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Beacuse it's a random process, scientists determine time taken for had the nuclei to decay. This is called the __ __
Half life
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Define the half life of a radioactive isotope
Time it takes for number of nuclei is half
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A radioactive isotope has half life if 15 days and internal count rate of 200 counts/s. Determine count rate after 45 days.
45/15 = 3 (count rate would halve 3 times) so on day 1 = 200 count rate. Day 15 = 100. Day 30 = 50. Day 45 = 25
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Is there always radiation around us?
Yes
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What's this radiation called?
Background radiation
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A natural resource of background radiation includes __ (e.g granite)
rock
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Cosmic rays are also an example of a natural source for background radiation. What are they?
High energy particles that travel through space and crash into earth's atmosphere
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What's a source for cosmic rays? (stars...)
Supernova (exploding stars)
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Nuclear weapon testing is an example of a __ source for bg radiation
Manmade
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Why is this a source?
it has released radioactive isotopes into environment for decades and isotopes still remain as bg radiation
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Nuclear accidents are also a man made source for bg radiation. True?
Yes
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What can effect your exposure to background radiation?
Location, occupation
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Alpha particles can be stopped by...
piece of paper
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Beta particles can be stopped by a few mm of ___
Aluminium
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Gamma is stopped by...
Several cm of lead
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When radiation collides with an atom, what happens?
Atom gains/loses electrons. They become charged (ions)
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Alpha particles are very ___ ionising (make lots of ions)
Strongly
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Beta particles are quite ___ ionising
Strongly
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Gamma is __ ionisng
Weakly
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Why are alpha particles harmful?
They can crash into cells and damage DNA, but are stopped by dead skin cells so don't harm living cells. But If breathed in, can damage lungs.
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In a smoke detector, they're two metal plates, connected to a ___ so one plate is positive and one negative
Battery
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There's also a radioactive element that reasese...
Alpha radiation
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The alpha particles make the air particles charged. How?
Alpha particles are very ionising so when collide with air, they make them ions
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The ions then move to...
Oppositely charged plate
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Meaning we have a small c___ between plates
current
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What happens when there's smoke particles as well? (how does it cause alarm)
Smoke particles attach to ions and stop them from moving, reducing current, setting off alarm
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Why are alpha particlues used?
Alpha are the most ionising and smoke detectors work by ionisation. Also alpha is easily stopped so won't pass out of detector casing (beta/gamma would pass and become harmful)
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Other cards in this set

Card 2

Front

Some isotopes have an unstable nucleus so to become stable they give out ___

Back

Radiation

Card 3

Front

radioactive decay is a r__ process

Back

Preview of the front of card 3

Card 4

Front

Undergoing radioactive decay is when...

Back

Preview of the front of card 4

Card 5

Front

Activity is the rate that an unstable nucleus ___

Back

Preview of the front of card 5
View more cards

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