PHYA5 ~ 20th June 2013 ~ A2 Physics

Thanks a lot - that's great.

Sorry to hear there's no Applied option stuff, if you e-mail the admins it might be a website error, it might be worth a try! But for the core there's still something like 100 pages of questions :smile:

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Reply 541

mrwho

Original post by laser174572

Sorry to hear there's no Applied option stuff, if you e-mail the admins it might be a website error, it might be worth a try! But for the core there's still something like 100 pages of questions :smile:

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I deleted that comment because it sounded rude, but I guess you saw it anyway! Apparently, though, applied comes under 'core', which I didn't realize. The 'packs' only had nuclear and not applied, but there's a bunch of past papers for applied physics from the old spec and that's great, so thanks again! I still don't see why applied physics isn't in the AQA revision book though.

Reply 542

jackerharder

Original post by Pinkhead

Try reading through this, especially the bit under ''Moderation of Fast Neutrons''
http://hyperphysics.phy-astr.gsu.edu/hbase/nucene/moder.html

Yes, I understand all of the moderation process, but I don't understand how the word 'scattering' can be linked to it? Does it just mean that the nuetrons released in fission go all different directions?

Reply 543

bugsuper

8

Original post by JRP95

You Only need around 100?! What did you get in the ISAs and in unit 4?

I got 120 in Unit 4, and 58 in the ISA. I think it's 270/300 for an A*, so I guess that leaves me with 92 to get...

Reply 544

smith50

6

Could anyone help me on this question please

Thanks,
Smith

Reply 545

bugsuper

8

The process of decay into calcium is 8x more likely than the process of decay into argon. This means that, for every argon atom, you can assume there will be 8 calcium atoms somewhere.

The tricky part comes in interpreting these relative proportions:

If there are 5 potassium atoms for every argon atom, then we know that there must also be 8 calcium atoms (because of that argon atoms.) This means that, initially, when the rock was formed, there were 14 potassium atoms (5 that still haven't decayed, 8 that became calcium, and one that became argon.) Using the half-life of potassium, which I imagine was given you, you can work out how long it would take for 14 potassium atoms to decay into 5 in the usual way.

Reply 546

cooldudeman

18

Original post by bugsuper

I got 120 in Unit 4, and 58 in the ISA. I think it's 270/300 for an A*, so I guess that leaves me with 92 to get...

Damnnn I got 57 in isa. Is that 54ums?

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Reply 547

bugsuper

8

I don't know the conversion rates off the top of my head, but they'll be on the AQA website (if you did it in January, anyway.)

It certainly won't be LESS than around 54 ums anyway

Reply 548

JRP95

2

Original post by bugsuper

I got 120 in Unit 4, and 58 in the ISA. I think it's 270/300 for an A*, so I guess that leaves me with 92 to get...

Wow you've dropped only 2 ums this whole year so far... So you've basically got an A*

Reply 549

fayled

9

Original post by bugsuper

I got 120 in Unit 4, and 58 in the ISA. I think it's 270/300 for an A*, so I guess that leaves me with 92 to get...

120UMS for me in unit 4 too, but we do the EMPA so I don't have the comfort of knowing my practical marks unfortunately. Also, I'm Oxford too :smile:

Reply 550

bobthebuilder

anyone who does astro, can you help me out pls?
i'm slightly confused about the definition of a black body,
if it absorb all wavelengths of all electromagnetic radiation, how can it emit all wavelengths of em radaition too?

Reply 551

amish123

Original post by bobthebuilder

anyone who does astro, can you help me out pls?
i'm slightly confused about the definition of a black body,
if it absorb all wavelengths of all electromagnetic radiation, how can it emit all wavelengths of em radaition too?

Thermal equilbrium I suspect, what energy it gains must be radiated to maintain this equilibrium. The radiation is emmited in accordance with Planck's law (black-body curve).

Reply 552

amish123

Original post by bugsuper

I don't know the conversion rates off the top of my head, but they'll be on the AQA website (if you did it in January, anyway.)

It certainly won't be LESS than around 54 ums anyway

Hey, I got pretty much the same results as you so far in Physics at A2, has your ISA been moderated at all?

Reply 553

bugsuper

8

Original post by amish123

Hey, I got pretty much the same results as you so far in Physics at A2, has your ISA been moderated at all?

I don't know about moderation, although I remember our Physics teacher very carefully explaining to us that grades may go up as well as down when we were given them. I think you only get your final grade in June, although I may be wrong... anyone know about ISA moderation procedures?

Reply 554

JayJay95

Hey guys

Just wanted to ask, are we supposed to use the atomic mass of an electron when calculating the mass defect in the binding energy section?

Reply 555

bugsuper

8

Original post by JayJay95

Hey guys

Just wanted to ask, are we supposed to use the atomic mass of an electron when calculating the mass defect in the binding energy section?

Since the changes of binding energy only apply to the nucleus, I doubt that you should - because the electron mass would presumably be conserved as electrons. Maybe if you were calculating the mass changes during electron capture, or something like that.

Reply 556

JayJay95

Original post by bugsuper

Since the changes of binding energy only apply to the nucleus, I doubt that you should - because the electron mass would presumably be conserved as electrons. Maybe if you were calculating the mass changes during electron capture, or something like that.

Oh yeah that makes sense thanks :biggrin:

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Reply 557

ehtisham_1

Hey guys on the topic of moderation, our isas got moderated last year and they got marked down as we may have done did the experiment wrong, for whatever reason it ended up getting marked down from an A to an E, so you never know with is as unless your 100 percent you've done the experiment correctly and your teachers marked it right.

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Reply 558

Beth_L_G

10

Does anyone happen to have a copy of any of the past papers with the answers written on? I have written out answers on printed past papers but I'm a bit of a cripple and so can't be bothered to go upstairs and get them :tongue:

Reply 559

jimmy_95

What are your opinions on the isa grade boundaries this year? Do you think they will go up, down or remain the same as last year?

PHYA5 ~ 20th June 2013 ~ A2 Physics

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