AQA Physics A - PHYA5 (18/06/12) - Exam thread

Reply 1180

Insanity514

15

Original post by Reminisce

Guys, for Astro, the second predominant absorption line for the B star is Helium right?

Yes

Reply 1181

Lucster

6

Has someone got a copy of the paper?

Reply 1182

kimmey

7

for the 2.6 x 10^9 one u could also check to see if it was right using the graph u plotted which was quite nice, also anyone else get 15s, and 3.68x10^-3 for the ratio thing, anyone doin medical get 109 or 106dB ?cant remember which one :smile:

Reply 1183

Netferatu

2

Aaaaaaaaaaaaaagh!!! 5c what the heck man!!!!!!!!!!!!!!! Why are the physics exams this year so haaard!!!!!!!

:'(

Reply 1184

LookIt'sPete

12

Original post by robthefool

The last question for astrophysics - quasars are very bright?
the distance was about 270MPc or something - needed to remember to covert to kms^-1
for the first paper, the 2nd part of the thermal heater I got 15 seconds
which star is closer? bellatrix
What class is it in? B
why are there no hydrogen balmer lines in the other star? it's cooler, so in lower spectrum, not hot enough for electrons in shell n=2
telescope 6 marker - I talked about uv telescope - have to be in space, atmosphere ozone absorbs uv. Radio can be on ground, atmosphere doesn't distort radio waves, big collection dish because radio waves have long wavelenth. Gamma ray telescopes small because gamma rays have small wavelength, in space because gamma rays are absorbed by earth atmosphere

Anyone want to tell me if that is correct?

I put quasars are powerful radio sources.
I got betelgeuse as closer
The rest the same, but I did radio, IR and visible light for the telescope question.

Reply 1185

Lucster

6

Original post by jlnbello

did you get kinetic enrgy as p.d multiplied by electron charge then for wavelength just use E=hc/lambda?
and for those graphs i drew a curve for the first one then a straight line for the raiuds against nucleon number, what did you guys sketch?

Was the Ek question on the applied physics paper or turning points?

Reply 1186

jammysmt

5

Original post by savage903

For Pb nucleus binding energy people get like 1600MeV or something like that.
Got 62000 foR Activity of gamma source. 15 seconds for heating. 2.6x10^9 years for uranium isotope question. Anyone get these answers?

Yey, all sounds very familiar to me. :smile:

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Reply 1187

kimmey

7

Original post by FrightBright

I got 0.34 moles

NOOOOOOOOOOO FUUUUUUUUUU

im pretty sure it was 0.257, anyone else ?

Reply 1188

SillyEddy

18

Original post by Reminisce

Guys, for Astro, the second predominant absorption line for the B star is Helium right?

Yep.

Did you write about how the other star was too cold to have hydrogen lines? I wrote that at class M, metals are made such as titanium oxide. As those are stars below 3500K and that one was 2400K wasn't it?

Reply 1189

number23

15

probably the hardest exam paper ive done :frown:

really didnt like section a

Reply 1190

rub em out

7

Original post by savage903

For Pb nucleus binding energy people get like 1600MeV or something like that.
Got 62000 foR Activity of gamma source. 15 seconds for heating. 2.6x10^9 years for uranium isotope question. Anyone get these answers?

I got 83 years, sure its not 2.6x10^9 seconds rather than years? I hope so anyway :/

Reply 1191

jammysmt

5

Original post by kimmey

for the 2.6 x 10^9 one u could also check to see if it was right using the graph u plotted which was quite nice, also anyone else get 15s, and 3.68x10^-3 for the ratio thing, anyone doin medical get 109 or 106dB ?cant remember which one :smile:

I got something like 99dB. I thought since intensity is wm-2 you had to find area of sphere 5m away.

This was posted from The Student Room's iPhone/iPad App

Reply 1192

Hazza616

1

Original post by kimmey

im pretty sure it was 0.257, anyone else ?

Yeah it was 0.257.

Reply 1193

savage903

8

Original post by FrightBright

Yes to all except activity :frown:

, talk me through what you did

i did 0.62/4x10^-3 . then i did that answer times 400 and got 62000.

Reply 1194

SillyEddy

18

Original post by kimmey

im pretty sure it was 0.257, anyone else ?

Can't remember for sure, but I believe my answer was more towards 0.257 than 0.32. I think it might've been around 0.28 that I wrote. Not sure.

Reply 1195

matthew769

18

Original post by rub em out

I got 83 years, sure its not 2.6x10^9 seconds rather than years? I hope so anyway :/

2.6x10^9 years

Reply 1196

savage903

8

Original post by kimmey

for the 2.6 x 10^9 one u could also check to see if it was right using the graph u plotted which was quite nice, also anyone else get 15s, and 3.68x10^-3 for the ratio thing, anyone doin medical get 109 or 106dB ?cant remember which one :smile:

I got 98dB

Reply 1197

LookIt'sPete

12

Original post by savage903

i did 0.62/4x10^-3 . then i did that answer times 400 and got 62000.