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

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1. (Original post by Dizzy in my Head)
Anybody remember any other questions and answers they'd like to share?

1. Complete the feynmann diagram. (3 marks)

Shown in the thumbnail.

This is what I did, not sure if it's right. Please, people, I can't do this on my own!
thats right. Mind if I add it to my mark scheme ?
2. 1. State what the ionisation energy is.

The minimum amount of energy that is needed to excite the electron from one energy level to transition to the ground state.

What I put, feel free to disagree.
3. (Original post by Dizzy in my Head)
1. State what the ionisation energy is.

The minimum amount of energy that is needed to excite the electron from one energy level to transition to the ground state.

What I put, feel free to disagree.
erm i put the 'minimum energy required to liberate an electron completely from the atom'. which i believe to be correct.
4. (Original post by maths134)
thats right. Mind if I add it to my mark scheme ?
Haha, sure, knock yourself out - I've been putting a few answers up, but I kind of need help with the six mark question, I know just bits and pieces.
5. what did you put for the 1st Q? I got nucleus
6. (Original post by fGDu)
not sure 3. is correct

4. Which of these two interactions cannot take place [COLOR=&quot;Red&quot;]The second interaction because leptopn number is not conserved[/COLOR]

5. Why must the charge of X be 0? [COLOR=&quot;Red&quot;]To conserve charge (0-&gt;-1+1)[/COLOR]

6. Which is the most stable particle in this interaction? [COLOR=&quot;Red&quot;]Proton[/COLOR]
I thought it was the top equation that doesn't work.
There are no leptons involved, so it is the Strong Interaction. And in this type of interaction Strangeness has to be conserved i.e it CAN'T be + or - 1 on either side.

The bottom equation was something = muon + antineutrino, which is 1 + -1 lepton = 0.

Anyone else agree?
7. (Original post by maths134)
erm i put the 'minimum energy required to liberate an electron completely from the atom'. which i believe to be correct.
Damn, yeah - the energy needed to remove an electron from the atom - why am I so stupid? I'll fail for sure now if I made mistakes like this the whole way through!
8. What was the neutral particle that decayed. question oneeeee
9. (Original post by TooEasy123)
I thought it was the top equation that doesn't work.
There are no leptons involved, so it is the Strong Interaction. And in this type of interaction Strangeness has to be conserved i.e it CAN'T be + or - 1 on either side.

The bottom equation was something = muon + antineutrino, which is 1 + -1 lepton = 0.

Anyone else agree?
Yeah, I got the top equation, too, because there wasn't any neutrino to conserve the pion-ness.

And I put weak interaction, because I just did. Because I'm stupid like that. Anyone got a definite answer to that?
10. (Original post by TooEasy123)
I thought it was the top equation that doesn't work.
There are no leptons involved, so it is the Strong Interaction. And in this type of interaction Strangeness has to be conserved i.e it CAN'T be + or - 1 on either side.

The bottom equation was something = muon + antineutrino, which is 1 + -1 lepton = 0.

Anyone else agree?
A muon has no lepton number

EDIT im an idiot goodbye 1 more mark
11. (Original post by Aish93)
what did you put for the 1st Q? I got nucleus
Thats wrong mate, unlucky. Good luck in the retake
12. Would you get marks for the proof question if you did the product of resistors in parallel / sum of resistors in parallel = (3+3) x 3 / (3+3) + 3 = 18/9 = 2 ohms, plus the 3 ohm resistor in series gives 5 ohms?

This is included in the NT book and its basically using the 1/R formula in a different way.
13. (Original post by Dizzy in my Head)
Yeah, I got the top equation, too, because there wasn't any neutrino to conserve the pion-ness.

And I put weak interaction, because I just did. Because I'm stupid like that. Anyone got a definite answer to that?
Isn't it the bottom equation because I used the insert sheet and saw both of the products had a lepton number of -1, meaning the thing that decayed (can't remember exactly) would have a lepton number of -2, to conserve lepton number, which it doesn't?
14. (Original post by Lucy149)
What was the peak to peak voltage of that ac source?
The Y-sensitivity was 0.5V per division (if I remember correctly), and the line length was 8 divisions (4 up, 4 down), therefore 0.5x8=4V.

Would you get marks for the proof question if you did the product of resistors in parallel / sum of resistors in parallel = (3+3) x 3 / (3+3) + 3 = 18/9 = 2 ohms, plus the 3 ohm resistor in series gives 5 ohms?

This is included in the NT book and its basically using the 1/R formula in a different way.
I think that was what you were supposed to do. That's what I did anyway.

I thought it was the top equation that doesn't work.
There are no leptons involved, so it is the Strong Interaction. And in this type of interaction Strangeness has to be conserved i.e it CAN'T be + or - 1 on either side.

The bottom equation was something = muon + antineutrino, which is 1 + -1 lepton = 0.
The bottom equation didn't work. It was an antimuon and an antineutrino, not a muon, which comes to L = -2. The muon was positively charged. Quite sneaky tbh.
15. For ionisation energy:
Minimum energy to remove an electron from an atom
In a gaseous state
16. (Original post by nkah)
Isn't it the bottom equation because I used the insert sheet and saw both of the products had a lepton number of -1, meaning the thing that decayed (can't remember exactly) would have a lepton number of -2, to conserve lepton number, which it doesn't?
Yup, thats exactlly what i did. I only realized once i saw the forumla sheet
17. (Original post by Spas_13)
Thats wrong mate, unlucky. Good luck in the retake

It asked for two baryons, one of which is a neutron (though you needed to state two - but you still got one mark if you didn't), the other a proton.

The nucleus is a collection of neutrons and protons, and it wanted a specific answer.
18. For the proof question i proved that the resistance of the resistors was 3, using my answer of 5 ohms from the previous question - would i still get marks for that?
i.e. i did 1/2r + 1/r = 1/rt
rt = 2r/3

2r/3 + r = 5
5r = 15
r = 3
19. i dont think we have mentioned the one in the first question yet about whether particle X was a lepton baryony or meson
i put baryon but i wouldnt count on any of my answers
20. (Original post by fGDu)
A muon has no lepton number

EDIT im an idiot goodbye 1 more mark
Yeah but it has a muon-lepton number of 1. and im pretty sure the other was was a muon-antineutrino. so thats -1 muon-lepton number.

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