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AQA Physics Unit 1 PHYA1 20th May 2013

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Reply 140
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Goods
16
What does everyone do as regarding sig fig?
Reply 141
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OliverG
2
3sf as standard, but if the question says to a reasonable number of sig figs, use the number in the question. For example, if you have a reading of 1.2V, do that question to 2sf.
Reply 142
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OliverG
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Also, can we expect any 6 markers on oscilloscopes, and if so, does anybody have a link to the relevant question? Thanks!
Reply 143
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acsecnarf
Does anyone know the full list of possible experiments for unit 1? thanksss
Original post by OliverG
Also, can we expect any 6 markers on oscilloscopes, and if so, does anybody have a link to the relevant question? Thanks!


Very unlikely... it was the 6 marker last year :smile:
Reply 145
Avatar for Xiomara
Xiomara
18
Original post by posthumus
Very unlikely... it was the 6 marker last year :smile:


I remember sitting that! It was hideous :frown:

I've done 4 past papers and a HSW 1 or 2 marker (i.e, why do we validate this hypothesis experimentally) has popped up in three of them. Anyone got a list of exactly what AQA want us to know regarding that?
Reply 146
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Tit
1
Quick question: If a proton is the most stable baryon and therefore doesn't decay, how can beta-plus decay (in which a proton decays via weak force into a neutron, positron and neutrino) exist?
Reply 147
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Xiomara
18
Anyone got bullet point tips on what to include for 6 markers? I thought I understood them, but I got given 2/6 on one of those questions today!
In 1 b ii, why won't the smallest energy photon be n4 to n3 as this gives you the smallest value?


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Original post by Jimmy20002012
In 1 b ii, why won't the smallest energy photon be n4 to n3 as this gives you the smallest value?


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Because n=1 is the ground state of the atom :smile: so if the electron actually jumps up to n4 and then back to ground state (remember always goes back to ground state) then quite the opposite is happening... your getting the highest energy photons

Original post by Xiomara
Anyone got bullet point tips on what to include for 6 markers? I thought I understood them, but I got given 2/6 on one of those questions today!


Ah yes the 6 markers are such a pain, I prefer it when the 6 marker is applying theory (like in unit 4) otherwise it's pointless :smile:
I haven't started preparing for unit 1 yet (I know... lol -_-) but I will probably focus on the potential six marker over the weekend, so I'll send you any bullet points I do make :smile: But revision guides usually do have the bullet points of pretty much all experiments you should know about...?
Original post by posthumus
Because n=1 is the ground state of the atom :smile: so if the electron actually jumps up to n4 and then back to ground state (remember always goes back to ground state) then quite the opposite is happening... your getting the highest energy photons



Ah yes the 6 markers are such a pain, I prefer it when the 6 marker is applying theory (like in unit 4) otherwise it's pointless :smile:
I haven't started preparing for unit 1 yet (I know... lol -_-) but I will probably focus on the potential six marker over the weekend, so I'll send you any bullet points I do make :smile: But revision guides usually do have the bullet points of pretty much all experiments you should know about...?


So basically it cannot excite to n=4 as the energy of the incident electron is 12.1ev, and you would need 12.75ev in order to reach this energy level. Pretty badly worked question, you kid of have to work backwards


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Original post by Jimmy20002012
So basically it cannot excite to n=4 as the energy of the incident electron is 12.1ev, and you would need 12.75ev in order to reach this energy level. Pretty badly worked question, you kid of have to work backwards


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No they're excited to all 3 (n=2,3 &4)... hence why three different energies are emitted... the electron that goes from n=2 to ground state will emit the lowest frequency. The trick I guess here is that, you take into consideration that electrons in any shell will always go back down to the ground state (in this case n=1). The further the electrons will be from ground state (away) the more energy they have gained... and therefore will release the most energy :smile:

EDIT: Oh and also having through about what you said... I think your right about 12.1 eV not being efficient energy to promote it to n=4 anyway. Sorry it's been far too long since I've studied this unit :tongue:
(edited 10 years ago)
Could anyone help me in the two question in the attached document?


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Original post by Jimmy20002012
Could anyone help me in the two question in the attached document?


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Don't hold me to this, but wouldn't it just be 100ohms and 50ohms?

They aren't in parallel, so what is there to calculate..? That's too simple though, but I haven't a clue what else you could do with the numbers..

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Original post by Jimmy20002012
Could anyone help me in the two question in the attached document?


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Does it help if I redraw it like this?
(edited 10 years ago)
lesketch24.png3.9KB
Original post by x-Sophie-x
Don't hold me to this, but wouldn't it just be 100ohms and 50ohms?

They aren't in parallel, so what is there to calculate..? That's too simple though, but I haven't a clue what else you could do with the numbers..

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It's a nice little tricky question... :wink:
Here is the link to the paper:

http://filestore.aqa.org.uk/subjects/AQA-PHYA1-W-QP-JUN10.PDF

How would you do 3 bii and 3ci, never come across a question like this before???


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Original post by Felix Felicis
It's a nice little tricky question... :wink:


I really hate it when you appear out of nowhere, and answer what seems like every maths related question!

Indeed it is xD
But I still see the same thing! :redface:

Is the second answer 37.5 Ohms by any chance?

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(edited 10 years ago)
For the photoelectric effect section, are we meant to know why it CAN'T be explained by the wave theory or just how it CAN be explained by the photon model?
Original post by physicshelpme
For the photoelectric effect section, are we meant to know why it CAN'T be explained by the wave theory or just how it CAN be explained by the photon model?


I think we need to know both.
You just need to mention the threshold frequency, right?

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