PHYA5 ~ 20th June 2013 ~ A2 Physics

Reply 1980

Does anyone have an 'unofficial mark scheme' for the medical physics?

Reply 1981

Someone has kindly put up the papers on the following thread, thought I'd link it for anyone who was looking for them. :smile:

http://www.thestudentroom.co.uk/showthread.php?p=43379911&highlight=phya5%20june%202013

Reply 1982

bugsuper

8

You know what? I read that last question on the core part again, thanks to these papers coming up, and I genuinely think that the "or" part isn't a major problem (which is good news for me.)

The experiment is there to determine which types of radiation are being emitted by the source. The question merely suggests two properties of the radiation that might be used to investigate it - it doesn't explicitly say "either/or"

Reply 1983

jarasta

12

Original post by bugsuper

You know what? I read that last question on the core part again, thanks to these papers coming up, and I genuinely think that the "or" part isn't a major problem (which is good news for me.)

The experiment is there to determine which types of radiation are being emitted by the source. The question merely suggests two properties of the radiation that might be used to investigate it - it doesn't explicitly say "either/or"

What do you mean, it says 'The experiment described should allow you to determine how
the intensity of radiation varies with distance in air or with the thickness of suitable
absorbers.''.
If it says should, surely it means, it has to be the geiger tube one, which is the only one that lets you work out intensity in air and thickness of absorbers. So the ionisation chamber may do it, but it won't do the absorption thing, magnetic fields and cloud chamber won't do either of those things so clearly AQA isn't asking you to describe those experiments.

Reply 1984

bugsuper

8

The experiment I described used both properties - you can use a geiger counter to work out how the intensity of radiation varies with distance in air, as well, just by moving it closer / further from the source.

What I'm saying is, I think they want you to describe a Geiger counter experiment that takes into account both different properties - range in air and penetrative power

But I might be wrong, it's just the idea I got from the question's wording

Reply 1985

jarasta

12

Original post by bugsuper

The experiment I described used both properties - you can use a geiger counter to work out how the intensity of radiation varies with distance in air, as well, just by moving it closer / further from the source.

What I'm saying is, I think they want you to describe a Geiger counter experiment that takes into account both different properties - range in air and penetrative power

But I might be wrong, it's just the idea I got from the question's wording

yeah i agree it was a geiger counter one with absorbers and no absorbers

Reply 1986

bugsuper

8

Original post by jarasta

yeah i agree it was a geiger counter one with absorbers and no absorbers

Yeah, that's what I described. I don't see how you can really be sure about the type of radiation with only one method.

Reply 1987

sam1w2e

8

Original post by bugsuper

Yeah, that's what I described. I don't see how you can really be sure about the type of radiation with only one method.

I'm glad I'm not the only one who thinks this too!! :biggrin:

Reply 1988

jarasta

12

Original post by bugsuper

Yeah, that's what I described. I don't see how you can really be sure about the type of radiation with only one method.

whoa he used the reply button!

well with the range on, if you got readings beyond 1m, lets say 2m to be safe, you could be pretty sure its gamma. Like wise the absorption one if you had reading from relatively thin lead you could be sure its gamma,the probability of detecting anything would be very low I imagine.

Reply 1989

cooldudeman

18

Original post by jarasta

whoa he used the reply button!

well with the range on, if you got readings beyond 1m, lets say 2m to be safe, you could be pretty sure its gamma. Like wise the absorption one if you had reading from relatively thin lead you could be sure its gamma,the probability of detecting anything would be very low I imagine.