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# Edexcel P2 Tomorrow Watch

1. I recall seeing a post for C2 where people asked questions and the next post answered and gave another question. Let's start one for P2

What is a model for radioactive decay?

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2. (Original post by harry_16)
I recall seeing a post for C2 where people asked questions and the next post answered and gave another question. Let's start one for P2

What is a model for radioactive decay?

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Half life; the average time it takes for half the undecayed nuclei to decay?

Explain why a resistor gets hot when a current passes through it?
3. My book says as its random - the model can be throwing a dice or flipping a coin
4. (Original post by sapphire79)
Half life; the average time it takes for half the undecayed nuclei to decay?

Explain why a resistor gets hot when a current passes through it?
The electrons colliding with the ions in the lattice of the resistor- these collisions give the resistor thermal energy
5. Sapphire, your definition for half life is correct but remember that the model is flopping a coin because the process of radioactive decay is completely random just like the probability of getting heads or tails.

Explain how alpha particles are used in a smoke alarm.

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6. (Original post by harry_16)
Sapphire, your definition for half life is correct but remember that the model is flopping a coin because the process of radioactive decay is completely random just like the probability of getting heads or tails.

Explain how alpha particles are used in a smoke alarm.

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There is a source of alpha radiation in the smoke alarm between two electrodes which emits a constant stream of alpha radiation. The alpha particles ionise the particles of air forming cations (+ve ions) & electrons (-ve). They both move to the opposite charged electrodes forming a small current across the gap. As long as there is a current the alarm does not sound. When there is a fire the smoke particles absorb the alpha nuclei reducing the flow of current across the gap. When the current stops flowing the alarm will sound.
7. What are the advantages of nuclear power?
8. (Original post by J__)
What are the advantages of nuclear power?
It's a fairly clean fuel, and also can produce plentiful energy with a small quantity of nuclear material.
9. Why do the properties of alpha particles make them very ionising?
10. (Original post by SophFlorence)
Why do the properties of alpha particles make them very ionising?
alpha particles have lots of energy so they can ionise lots atoms in a short distance?? im not sure

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11. How can a leak in a water pipe be detected?

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12. (Original post by ksj.11)
alpha particles have lots of energy so they can ionise lots atoms in a short distance?? im not sure

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Pretty much, yes! It's also because they are slow-moving. Thus, when moving past an atom, there's a higher chance of it coming into contact with it, and knocking an electron off. The part about the short distance is particularly right, because since they are slow-moving, they have a higher chance of coming into contact with an atom, and so will be stopped more quickly, hence they do not penetrate far into material.
13. (Original post by ksj.11)
How can a leak in a water pipe be detected?

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A gamma source is added to the water, and a GM tube is placed outside the water pipe. If there's a leak, the GM tube will detect higher levels of radiation than if there was not a leak.
14. How'd everyone find it?

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15. (Original post by SophFlorence)
How'd everyone find it?

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Found it really good!! You?
16. (Original post by J__)
Found it really good!! You?
AW, good! Yeah, also very good thanks!

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