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# AQA Physics Unit 1 PHYA1 20th May 2013 Watch

1. (Original post by westarmy)
:P well I'm pretty much doing the same! And you know what I meant
Hee hee! .....

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2. (Original post by chubuking)
i thought that the current is higher when the pd is lower as the temperature is lower (therefore the resistance is lower) hence if you calculate power using V^2/R since R is a smaller value the power rating will be larger?
Yes correct!
3. (Original post by chubuking)
the temperature is lower (therefore the resistance is lower) hence if you calculate power using V^2/R since R is a smaller value the power rating will be larger?
But V is also lower, so V^2/R isn't really of use (I think)
4. (Original post by suzan0101)
No way are you being serious wasn't the paper in jan hard enough

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I am not serious but it is more likely to be a hard paper.
5. im confused :s on the jan 2013 paper 2b how do you know the infomation required to form 1 electron?
6. (Original post by Micheal123456)
were did you get the infomation that you need that about of energy for 1 electron to be created?
Took me a while to figure out as well its actually in that table... on AS formulae sheet

You see that energy is for rest mass... So that's how much is needed to create an electron (and positron which has same rest mass) hence x 2 = 102 MeV
7. (Original post by Micheal123456)
were did you get the infomation that you need that about of energy for 1 electron to be created?
It is the rest energy of 1 electron. In a pair production, 2 are produced. It is also in the data formula sheet.
8. (Original post by StalkeR47)
I am not serious but it is more likely to be a hard paper.
Well it should be a easier paper. What makes you think it's going to be harder?

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9. (Original post by StalkeR47)
It is the rest energy of 1 electron. In a pair production, 2 are produced. It is also in the data formula sheet.
but the rest energy for an electron is 9.11x10^-31
10. (Original post by NedStark)
How do we know the current is lower?
V=IR voltage drops therefore current drops. Lower current means a lower heating effect and so the temperature also falls. Lower temperature results in lower resistance. This means that the current although being lower than before is higher than predicted based off the previous resistance and so P=IV is larger than you would expect for the reduced voltage

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11. (Original post by Micheal123456)
but the rest energy for an electron is 9.11x10^-31
That's rest mass. You need rest energy. Should be on the other side of the sheet in the table mate.
12. (Original post by Clarky747)
That's rest energy. You need rest mass. Should be on the other side of the sheet in the table mate.
ooooo i c thanks alot and does anti matter have the same rest energy as its particle?
13. (Original post by Goods)
V=IR voltage drops therefore current drops. Lower current means a lower heating effect and so the temperature also falls. Lower temperature results in lower resistance. This means that the current although being lower than before is higher than predicted based off the previous resistance and so P=IV is larger than you would expect for the reduced voltage

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Thanks a lot! that clears it up.

But at the beginning when you says voltage drops, therefore current drops. Does the resistance stays constant for that part?
14. (Original post by Micheal123456)
but the rest energy for an electron is 9.11x10^-31
NO!!!!!! This is the mass of a single electron. Not rest energy!
15. (Original post by Micheal123456)
ooooo i c thanks alot and does anti matter have the same rest energy as its particle?
yes! but I has opposite charge. your welcome!
16. Are rest energies on the data sheet or do you have to remember them. I cant seem to find them on the data sheet in the back of the Aqa text book
17. (Original post by StalkeR47)
NO!!!!!! This is the mass of a single electron. Not rest energy!
Rest mass is the same as rest energy?!

Oh actually never mind. I get what you mean now.

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18. (Original post by Mattmms)
Are rest energies on the data sheet or do you have to remember them. I cant seem to find them on the data sheet in the back of the Aqa text book
They're on the data sheet in a table

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19. (Original post by Mattmms)
Are rest energies on the data sheet or do you have to remember them. I cant seem to find them on the data sheet in the back of the Aqa text book
in a little table should be 0.5mev
20. (Original post by suzan0101)
Well it should be a easier paper. What makes you think it's going to be harder?

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To be honest, no one can predict lol. How are you supposed to predict. I just said what I thought.

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