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AQA Physics PHYA5 - Thursday 18th June 2015 [Exam Discussion Thread]

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Would we need to know the experimental details of Boyles, Pressure law, Charles law. Not sure if they would ask something like draw a diagram with the apparatus to find out the relationship between ... pressure and temp etc
Original post by DannySmith420
Theres more than 1 way to do this calculation however i think the easiest way to look at it is if the detector counts 0.62/s but this is only 1/400 of the photons emitted. So if the detector was on the source the count rate would be 248/s (0.62 x 400) this is the activity of the source however only a small part of it as the area of the detector is 1.5x10^-3 and the rays are emitted uniformly in all directions. The total activity of the source is how many emitted per second. As worked out in b(i) you know the ratio of the area of dectector to area of emitted rays. So use 248 ÷ this (3.684x10^-3) and you get 67000 Bq


ok, but what would be the point of a detector only detecting 1 in 400 photons that hit it?
Original post by johnh545
ok, but what would be the point of a detector only detecting 1 in 400 photons that hit it?


I'm guessing you can't get detectors that are 100% efficient.
June 14 is a godsend. You can drop 17 marks and still get full UMS. Praying we have similar grade boundaries for tomorrow!
Original post by slaven123
June 14 is a godsend. You can drop 17 marks and still get full UMS. Praying we have similar grade boundaries for tomorrow!


they tend to all have fairly low boundaries,
more often than not anyway.
Reply 2045
Could someone explain the signficance of abundance of hydrogen and helium in ration 3:1 as evidence of a hot big bang?
Just wondering, do we need to know how a black hole is formed?


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Original post by johnh545
they tend to all have fairly low boundaries,
more often than not anyway.


Only the past two years have been properly low! But yeah, they are generally pretty nice for unit 5
Original post by JaySP
Could someone explain the signficance of abundance of hydrogen and helium in ration 3:1 as evidence of a hot big bang?


at one point universe was like the star core, and fused hydrogen to helium meaning it was very hot and dense
6 marker predictions for astro and nuclear?
Original post by xela238
Just wondering, do we need to know how a black hole is formed?
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Just that it's created at the end of the lifecycle of a star whose core is more than 3 times the sun's mass.
This means that the neutrons can't withstand the gravitational forces and so it collapses to an infinitely dense point. This is the blackhole.
I believe we will be getting the R paper because I just heard that the AQA Biology students got an R paper
Someone give me a breakdown on how I should give S.F in questions which they have not asked for appropriate number of S.F
ImageUploadedByStudent Room1434546265.949254.jpg

Always get stuck on these sorts of questions, can someone give me a hand please

EDIT - just realised I can equate kinetic energy and eV

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(edited 8 years ago)
Are we expected to use 2.5m1-m2 ?
Original post by Disney0702
I believe we will be getting the R paper because I just heard that the AQA Biology students got an R paper


Does that to change anything?
Do we need to know how to fully derive pV = 1/3 N m (Crms)^2?
Original post by xela238
Does that to change anything?


All it means is we'll have a different paper from the one that was originally intended for us....

We shouldn't see a difference apart from the letter R on the paper's code. Don't know why everyone seems to think it's such a big thing!
Do we need to know how to fully derive pV = 1/3 N m (Crms)^2
Original post by Klaxoii
ImageUploadedByStudent Room1434546265.949254.jpg

Always get stuck on these sorts of questions, can someone give me a hand please

EDIT - just realised I can equate kinetic energy and eV

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Can I ask what unit this is for ?

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