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# PHYA1 - Physics Unit 1 Exam - 24th May 2011 watch

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1. (Original post by melon 314)
i found that paper so hard the electricity at the end and that six mark question. i wrote stuff down but i doubt i'll get anywhere near 6 marks for it !

what was I doing wrong on the last question i couldn't get the total resistance to match the resistance of each resistor ?
The resistance in the parallel reistors was (1/[3+3])+(1/3)=1/R . This gave R=2. You then add this value to the other resistor in the circuit (beacuse it's in series) giving you a total resistance of 5, which you worked out before The electricity on the last page was hard though haha
2. For the gradient i put it to like 3sg figs i think.. i worked out the gradient as 0.444 do you think i'd still get the full marks?
3. Yeah for negligible resistance I drew the line y=1.52.
So I got the EMF as 1.52.
I got resistance as the negative gradient so 0.453, rounded to 0.45.
The line B, I put as having twice the gradient as internal resistance doubled. So the gradient was -0.9 and y-intercept remains 1.52.

For the last question I got overall resistance as 5Ohms (10/2).
Then the next bit was just resolving the 3Ohm resistors until it equalled 5Ohms.
For the last 2 I got, 1.3A(2sf) and 2V although I'm unsure on these.

The decay was electron capture, Feynman diagram had a W+ boson, neutron, and neutrino.

The second out of the two reactions was impossible as lepton number wasn't conserved (0--> -2)

Unsure why the terminal potential difference increased as amps increased.

Two baryons: neutron & proton.

Strange particles have strange quarks.

First oscilloscope trace was a dot 2 boxes above original.
Vertical line because time base was off so no horizontal movement, and it's moving up and down so fast it appears a vertical line.

6 marker was describing excitation then deexcitation, and explaining how the lines were discrete because of only certain wavelengths therefore frequencies therefore energy were possible as only certain energy photons can be emitted as there are only discrete energy levels the electron can de-excite through.

S'all I remember, I'm open to correction, hope it helps
4. What was the answer to where did the electron come from or something like that.
5. (Original post by hwalker37)
The resistance in the parallel reistors was (1/[3+3])+(1/3)=1/R . This gave R=2. You then add this value to the other resistor in the circuit (beacuse it's in series) giving you a total resistance of 5, which you worked out before The electricity on the last page was hard though haha
oh crap i did 1/3+1/3+1/3 =1 +3 from the other resistor but its only 1 mark. but lost tonnes everywhere. looks like a retake in jan.

anyway what did point did everyone put for the 6 marker ?
6. Who else messed up the last two questions? -.-
7. (Original post by Limitless)
What was the answer to where did the electron come from or something like that.
come from an electron in one of the shells close by i think
8. (Original post by Limitless)
What was the answer to where did the electron come from or something like that.
Damn that question! I thought that as AQA don't mark negatively i would put down the sun, ionisation and another atom, no doubt they're all wrong though
9. I messed up big time, was really hard.
10. for the question about why the particle is strange was it because it has a strange quark? because i put antistrange as on the formula sheet it says that a strange quark has strangeness -1? :/
11. What did people put for what is ionisation?
12. (Original post by A level Az)
Who else messed up the last two questions? -.-
Me! this exam was haaard!
13. (Original post by anil10100)
Yeah for negligible resistance I drew the line y=1.52.
So I got the EMF as 1.52.
I got resistance as the negative gradient so 0.453, rounded to 0.45.
The line B, I put as having twice the gradient as internal resistance doubled. So the gradient was -0.9 and y-intercept remains 1.52.

For the last question I got overall resistance as 5Ohms (10/2).
Then the next bit was just resolving the 3Ohm resistors until it equalled 5Ohms.
For the last 2 I got, 1.3A(2sf) and 2V although I'm unsure on these.

The decay was electron capture, Feynman diagram had a W+ boson, neutron, and neutrino.

The second out of the two reactions was impossible as lepton number wasn't conserved (0--> -2)

Unsure why the terminal potential difference increased as amps increased.
Two baryons: neutron & proton.

Strange particles have strange quarks.

First oscilloscope trace was a dot 2 boxes above original.
Vertical line because time base was off so no horizontal movement, and it's moving up and down so fast it appears a vertical line.

6 marker was describing excitation then deexcitation, and explaining how the lines were discrete because of only certain wavelengths therefore frequencies therefore energy were possible as only certain energy photons can be emitted as there are only discrete energy levels the electron can de-excite through.

S'all I remember, I'm open to correction, hope it helps
As the current increases the internal resistance also increases I think? Because E = V + Ir, so current x internal resistance.

And I crossed out electron capture and wrote "proton-electron capture"! Will i lose a mark?

And there wasn't a single resistivity question either? Weird.
14. (Original post by amoo94)
for the question about why the particle is strange was it because it has a strange quark? because i put antistrange as on the formula sheet it says that a strange quark has strangeness -1? :/
It's because it has a strange/antistrange quark.
15. (Original post by melon 314)
oh crap i did 1/3+1/3+1/3 =1 +3 from the other resistor but its only 1 mark. but lost tonnes everywhere. looks like a retake in jan.

anyway what did point did everyone put for the 6 marker ?
For the 6 marker. I just put down a load of crap. They don't mark negatively so it's not that bad.
16. (Original post by A level Az)
It's because it has a strange/antistrange quark.
so i'd get the mark for just saying antistrange?
17. (Original post by amoo94)
for the question about why the particle is strange was it because it has a strange quark? because i put antistrange as on the formula sheet it says that a strange quark has strangeness -1? :/
It was strange quark.
You might get the mark for anti strange but I think it was asking generally not specifically. So a particle is strange if it contains a strange quark.
18. i put strangeness is only conserved in the strong interaction for that question didn;t have a clue guessing i won't be getting any marks for that
19. for the last one i worked out the pd of the resistor in serious which was current times resistance so 2x3=6. took that away from emf 10-6=4. so 4v in the parallel combination. there were two resistors with the same resistance so 4/2=2 which was the pd through w
20. (Original post by A level Az)
As the current increases the internal resistance also increases I think? Because E = V + Ir, so current x internal resistance.

And I crossed out electron capture and wrote "proton-electron capture"! Will i lose a mark?

And there wasn't a single resistivity question either? Weird.
Which direction was the W+ boson I put and arrow pointing left.

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