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Radioactivity Flashcards
Free GCSE Physics Cards on Radioactivity
From the properties of alpha, beta and gamma radiation to half life calculations and nuclear equations, these free Physics flashcards cover radioactivity for GCSE and A Level.
Question
What is radioactivity?
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Answer
The spontaneous emission of radiation from unstable atomic nuclei as they decay to become more stable. It is a random process unaffected by chemical or physical conditions.
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Question
What are the three main types of nuclear radiation?
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Answer
Alpha (α): 2 protons + 2 neutrons (helium nucleus). Beta (β): fast electron from nucleus. Gamma (γ): high-energy electromagnetic radiation.
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Question
What is the penetrating power and ionising ability of alpha, beta, and gamma?
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Answer
Alpha: least penetrating (stopped by paper/skin) but most ionising. Beta: stopped by a few mm of aluminium. Gamma: stopped only by thick lead/concrete, least ionising.
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Question
What is an alpha decay equation?
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Answer
The nucleus loses 2 protons and 2 neutrons: mass number decreases by 4, atomic number decreases by 2. Example: ²³⁸₉₂U → ²³⁴₉₀Th + ⁴₂He
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Question
What is beta-minus decay?
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Answer
A neutron in the nucleus converts to a proton, emitting a fast electron (β⁻) and an antineutrino. Mass number unchanged, atomic number increases by 1.
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Question
What is gamma radiation?
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Answer
High-energy electromagnetic radiation emitted from an excited nucleus after alpha or beta decay. No change in mass number or atomic number — just a release of energy.
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Question
What is half-life?
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Answer
The time taken for half the radioactive nuclei in a sample to decay. It is constant and characteristic for each radioisotope, independent of the amount present.
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Question
How do you calculate remaining activity after n half-lives?
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Answer
Remaining = Initial × (½)ⁿ. Example: after 3 half-lives, 1/8 of the original activity remains.
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Question
What is background radiation and give examples of sources?
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Answer
Low-level radiation always present in the environment. Sources: radon gas (largest in UK), cosmic rays, medical X-rays, food/drink, and small amounts from nuclear industry.
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Question
What is nuclear fission?
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Answer
The splitting of a large, unstable nucleus (e.g. ²³⁵U) into two smaller nuclei + neutrons + energy, triggered by neutron absorption. The released neutrons can trigger further fissions (chain reaction).
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