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

1. (Original post by QueNNch)
Ah ok lets see, I set June 2013 in the UMS converter and got:

Unit 1: 88
Unit 2: 106
Unit 3T: 39
Unit 4: 108
Unit 6T: 17
Unit 5A: ?

Total UMS marks yet (predicted of course): 358
When I added all the needed UMS for an A grade in June 2013, it was 480
So the difference is 122 UMS.
Looks like I won't probably land an A looking at that :/
What is total UMS acheivable and it seems like you really messed up 6T :l

scratch that..

you could get an A* if you haven't actually messed up 6T.
2. (Original post by betbi3etwerrd)
What is total UMS acheivable and it seems like you really messed up 6T :l
Total UMS achievable is 120 + 120 + 60 + 120 + 120 + 60 = 600
and yeah in 6T I got 33 out of 50

Now I used the UMS converter for June 2014 and it says I need 52 UMS in Unit 5A!

Woah the difference is so huge...
According to June 2013 I need 122 UMS
According to June 2014 I need 52 UMS
3. (Original post by QueNNch)
Total UMS achievable is 120 + 120 + 60 + 120 + 120 + 60 = 600
and yeah in 6T I got 33 out of 50

Now I used the UMS converter for June 2014 and it says I need 52 UMS in Unit 5A!

Woah the difference is so huge...
According to June 2013 I need 122 UMS
According to June 2014 I need 52 UMS
I do 6x instead and I feel it is far easier to get an A* because you only need around 38/55 to get the A*! (in 6x)
4. Just found this which might help people with an idea. Sorry if you can't make sense of it as it's been scribbled all over but it shows ums/raw conversions and %
5. (Original post by gcsestuff)
For turning points yes.

It's how between two plates an electron can act like a wave and jump across. As long as the gap is small enough and the potential difference is large enough. This is how electron tunnelling microscopes work.

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Hmmm I meant for the topic of binding energy? Its in the textbook but seems so confusing
6. (Original post by Sbarron)
Just found this which might help people with an idea. Sorry if you can't make sense of it as it's been scribbled all over but it shows ums/raw conversions and %
Thanks for that I used it and it still looks like I need ~120 UMS for an A minimum :\
Did not know that the coursework could make so much difference

Fingers crossed for lower grade boundaries compared to June 2013 and I can get an A...

What did you get for yours?
7. (Original post by Specter)
Hmmm I meant for the topic of binding energy? Its in the textbook but seems so confusing
What does the book say? We learnt very briefly. Just that an alpha particle uses the release of binding energy to overcome the Coulomb barrier and therefore gains kinetic energy and leaves the nucleus?

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8. Is a Quasar the name for a galaxy with a black hole in the centre, or the name for a black hole in the centre of a galaxy? If you get what I mean.
9. (Original post by Specter)
Hmmm I meant for the topic of binding energy? Its in the textbook but seems so confusing
The textbook doesn't even know what it's saying. In that they try to simplify what isn't an elementary concept.

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10. are there any past papers from before 2007? The link on the first page just has 2007 onwards.
11. Someone give me a concise definition of the metastable state?
12. (Original post by QueNNch)
Thanks for that I used it and it still looks like I need ~120 UMS for an A minimum :\
Did not know that the coursework could make so much difference

Fingers crossed for lower grade boundaries compared to June 2013 and I can get an A...

What did you get for yours?
I haven't done too well (messed up with stupid things) the unit 6 written part was AWFUL for me and I made some really really stupid mistakes on unit 4 too. I need a B overall but must get 101 UCAS points according to this on unit 5 now! I'm studying for hours ATM!! I'm desperate!! Lol
13. (Original post by Mehrdad jafari)
The textbook doesn't even know what it's saying. In that they try to simplify what isn't an elementary concept.

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I think I've learned it now although I'm far from full comprehension of it
14. Turning points chapter 1: "The emission of light from a discharge tube happens because the voltage applied to the tube is so high that it pulls electrons out of some of the gas atoms in the tube."

How can a high voltage (edit: by itself) pull off electrons from atoms?
15. (Original post by slaven123)
Is a Quasar the name for a galaxy with a black hole in the centre, or the name for a black hole in the centre of a galaxy? If you get what I mean.
Quasars are the most distant and most powerful observable objects.
Using inverse square law it is shown that they produce the same power output of several galaxies but variation in their output suggests they may be only the size of a solar system.
They are now believed to come from a super massive black holes at the centre of active galaxies.

They emit electromagnetic radiation from the whole spectrum.
16. (Original post by Sbarron)
I think I've learned it now although I'm far from full comprehension of it
Hello what exactly do you need help with I might be able to help
17. (Original post by AR_95)
Someone give me a concise definition of the metastable state?
A species, formed via beta decay of a parent nucleus, that is formed in an excited state and stays in this state for a prolonged period of time
18. This is all slightly confusing: If thermionic emission isn't used in a gas discharge tube where do the electrons come from? I am aware that they come from the cathode and some are apparently pulled off gas atoms by the high voltage. Where do the cathode ones come from and how does the "pulling off by high voltage" mechanism work. (It seems unlikely that a high voltage by itself can cause atoms to ionize but I could be wrong.)
19. (Original post by Protoxylic)
A species, formed via beta decay of a parent nucleus, that is formed in an excited state and stays in this state for a prolonged period of time
So I understand that there's a time delay before the daughter nucleus emits the gamma photon
The metastate, is when the daughter nucelus is excited and is yet to emit the photon to de excite/ return to ground state?

Also in my book it mentions this occurs in alpha decay, so why've you only limited it to Beta?

(Original post by PotterPhysics)
This is all slightly confusing: If thermionic emission isn't used in a gas discharge tube where do the electrons come from? I am aware that they come from the cathode and some are apparently pulled off gas atoms by the high voltage. Where do the cathode ones come from and how does the "pulling off by high voltage" mechanism work. (It seems unlikely that a high voltage by itself can cause atoms to ionize but I could be wrong.)

The high voltage , or higher potential difference, means that the acceleration of particles is also higher. Higher acceleration means higher force (F=ma) and also velocity so the collision is more likely to cause ionisation
20. Must we always put neutrino as a product of alpha decay for the marks?

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