random - cannot predict when/ which will decay/ spontaneous - not induces/ no external influence/ unaffected by extreme conditions
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describe alpha decay
+ helium nuclei/ very short range of few cm in air/ very ionising/ deflected by electric and magnetic fields
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Describe beta decay
- electron or positron/ daily ionising/ range of few mm in aluminium/ deflected by magnetic an dielectric fields
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Describe gamma decay
no charge/ short ranged EM waves/ weakly ionising/ range of few cm in lead/ not affected by electric or magnetic fields
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What is activity?
spontaneous emission of a stream of particle for em waves in nuclear decay/ number of decays per secodn
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What is the unit for activity?
Becquerel, Bq
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What is the decay constant?
probability of decay per nucleus per unit time
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describe the equation for activity
A = YN - N number of undecided nuclei/ Y must be in s/ larger decay constant, faster rate/ activity proportional to size of sample
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Define Half life
the time taken for the number of un-decayed nuclei to decrease to half its original number / Yt1/2 = 0.693
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Describe radioactive smoke alarms
weak source of alpha radiation close to two electrode/ radiation ionises air - current flows/ some absorbs radiation, stops or reduces current - alarm
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Describe radiocarbon dating
living organisms absorb C-14 isotope/ once dead takes in no more and activity starts to fall/ number of isotopes or activity is measured and compared to living sample
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Describe radioactive decay vs. capacitor discharging in a C-R circuit
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Other cards in this set
Card 2
Front
describe alpha decay
Back
+ helium nuclei/ very short range of few cm in air/ very ionising/ deflected by electric and magnetic fields
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