PHYA5 ~ 20th June 2013 ~ A2 Physics

Indeed. If the focal length was a few mm, we'd have less of a case, as that would clearly be an eyepiece, but I think there's a bit of ambiguity

You shouldn't do, they usually only penalise you once I wouldn't worry

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Any chance of 54 marks being an A. I really doubt it considering it was not that bad. It was answerable but I made stupid mistakes.

Any chance of 54 marks being an A. I really doubt it considering it was not that bad. It was answerable but I made stupid mistakes.

Section A:
1a) define an atomic mass unit (1 mark)
b) describe and explain the difference between the mass of a He nucleons and the nucleons that make (something like that) (2 marks).
c) explain the high energy in the stars to undergo fusion (3 marks)
d) equations in the CNO cycle (3 marks)
e) mass defect question with four hydrogen-1 nuclei making a helium nucleus and two positrons (3 marks)
2a) describe a way to reduce the energy output of a nuclear power plant (2 marks)
b) give a source of high radiation from a nuclear power station (1 mark)
c) explain and describe the nature of the radiation emitted from the moderator after collision with a neutron transferring kinetic energy. (2 marks)
d) the collision with a neutron and a moderator is elastic, what happens to the neutron after collision (something like that) (2 marks).
3a)i) cola at 3 degrees is put into a glass at 30 degrees, show that the final temperature of the cola is 8 degrees. (2 marks)
a)ii) ice at zero degrees is put into the cola and brings it to 3 degrees (if I remember right). Calculate the mass of the Ice (3 marks). All values of C and l are given in these these questions.
4a) definition of an ideal gas (2 marks)
b) work out the number of moles in a gas of container volume 0.2 m^3. (2 marks)
c) calculate the density when the molar mass is given, give a unit (3 marks)
d) some air escapes from the cylinder when it is at higher altitude, find the new mass. (Not too sure about this one) (3 marks)
5) six marker QWC question on devising an experiment to test the radiation emitted from a source. (6 marks)

Please improve on this if possible. I did turning points, I'll try to make one for turning points, but I don't remember that one very well.

I presumed you had to choose one because it said or.... so i talked about the absorber experiment and the shortcomings, but the general experiment too and the principles behind it as well as describing it and talking about the safety precautions...


In terms of the paper itself, i found the written questions much easier. I normally depend on the maths but i made so many errors. The Astro 6 marker was beaut; there were so many points you could make about CCDs structure function advantages etc. I did say i'd use the lens as an objective (stupidly) lol. Apart from that, loved astro (except my wrong H value on the last question) especially the sneaky diffraction pattern graph for the Rayleigh Criterion

I needed 98/120 ish for an A* but given the sheer number of calculation errors i made (and missing out the last part of the pressure question) and the high grade boundaries for astro, i dont think itll happen :/ how did astro people find the paper?

Thanks. I don't know why I thought almost 7 was close to 8 anyway. XD

Did anybody else think question 2 (Specific heat capacity question) was evil?

There was a lot of work for only 2 marks on the first bit which was annoying...

Who managed to do the cola one.... ???

I did:

mcT=mcT

mc(3+T) = mc(30-T)

Then in the end I did 3+T ... & I got 7, I'm hoping this is only due to rounding though

No worries, a few people in my class messed up sochances are that itwont effect your mark too much

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Mine rounded to 7 too. I can't even remember what I did but it looks similar to the working out you've done.

I'm absolutely fuming at myself for not converting anything to Kelvin. I blame the all-nighter I pulled. What a waste, but hopefully I'll get the ECF.