You are Here: Home >< Physics

# AQA Physics PHYA4 - 20th June 2016 [Exam Discussion Thread] Watch

1. (Original post by kingaaran)
Why is it wrong - you will get the marks if you write 2.7, the brackets are to show examiners what the other significant figure needs to be to ensure candidates have used a valid method.

In response to your second question, they've used the atomic mass unit, not the mass of the proton which is of course correct - on their formula booklet they clearly say u=1.661 x10^(-27)

Posted from TSR Mobile
Do we have to use the atomic mass unit then?

Posted from TSR Mobile
2. (Original post by kingaaran)
A positive ion will have weight going down and so if it is in equilibrium the electric force on it must be acting upwards.

The direction of the electric force is the direction a positive particle would go and thus it is upwards

Posted from TSR Mobile
So to hold an electron in equilibrium, field would be downwards?

Posted from TSR Mobile
3. (Original post by Yo12345)
The one with the thumb being the current and the fingers being the field direction?

Posted from TSR Mobile
No, check page 122 of the textbook, the dynamo rule.
4. (Original post by lucabrasi98)
1. It's not about what you get the marks for. I still got the question right, I just hate seeing them write 2.6 as and an answer when you the accurate solution is 2.666. That was obviously an accident by them. They pull stuff like that every year.

2. Honestly I didn't notice the atomic mass unit. But I still fail to see why they're using that when an alpha particle is just 2 protons and 2 neutrons. What would I do in an exam then? And what's the point of specifying proton and neutron masses if sometimes they just use atomic mass instead?

3. The whole issue with whether to use rounded answers for the next question or accurate answers still gets on my nerves. I wouldn't mind if they just settled on one way but they genuinely change their minds as they see fit. Which is a problem as sometimes using the one they don't want gets you "incorrect" rounding. E.g them wanting 2700 but you getting 2763 and rounding to 2800 because you either used the accurate or rounded answer from the last question and they wanted you to use the opposite
1. 2.666 is not accurate because your speed is only to two significant figures, meaning any other significant figures after the second you cannot be certain about.

2. The atomic mass unit is defined such that both the proton and neutron have mass 1amu. You can use the separate ones for accuracy in greater significant figures or if you only want to know the mass of some protons, but as far as the required accuracy of the questions go, amu is fine to use.

3. Well if you use an answer correct to two significant figures and they use the full answer correct to 199283737126271891 significant figures, you will both still be correct to two significant figures. So it doesn't matter. The best bet obviously is to use the most accurate one, because you never can be wrong.

Don't look too much into this

Posted from TSR Mobile
5. (Original post by Yo12345)
So to hold an electron in equilibrium, field would be downwards?

Posted from TSR Mobile
Yes, because a downwards field will create an upwards force an electron - which is exactly what you need to balance it in equilibrium!

Posted from TSR Mobile
6. Can someone help me with question 19 on june 2014, https://60abffc9b401b1c0936e01291c15...%20Physics.pdf
I dont understand how you are meant to get 200, I got 600 when I did:

c = Q/V
1600/x = 400/(x-2)
1600x - 3200 = 400x
1200x = 3200
x = 8/3
c = 1600/(8/3)
c=600
7. Hi all,

I posted about having some A2 paper packs I created myself before

Here is another one ... this one is multiple choice and I go through in the mark scheme I created how you should be thinking through each question.

Sorry there is only 7 questions in this one, but the mark scheme is quite good and took a bit longer to make than the paper did.

Again if you would like more please email me at; [email protected]

Cheers,

Will
Attached Files
8. AQA A2 Physics Style paper - Section A - Paper 1 Mark Scheme.doc (31.5 KB, 55 views)
9. AQA A2 Physics Style paper - Section A - Paper 1.doc (32.0 KB, 69 views)
10. (Original post by cmrol)
Can someone help me with question 19 on june 2014, https://60abffc9b401b1c0936e01291c15...20Physics.pdfI dont understand how you are meant to get 200, I got 600 when I did:c = Q/V1600/x = 400/(x-2)1600x - 3200 = 400x1200x = 3200x = 8/3c = 1600/(8/3)c=600
using E = (1/2)cV2

(1) 1600 = (1/2)cV2
(2) 400 = (1/2)c(V-2)2

4 = [cV2]/[c(V-2)2]
4(V-2)2 = V2
4V2 - 16V + 16 = V2
3V2 - 16V + 16 = 0
V = 4, V = 4/3

sub V = 4 into (1), 1600 = (1/2)16c
sub V = 4 into (2), 400 = (1/2)4c

1600 = 8c

c = 200
11. Hello Again,

In case the other unit 4 paper I have finished got lost in this thread for yo, I have attached the other paper and its mark scheme.

Enjoy !!,

Will
Attached Files
12. AQA Style A2 physics past paper 1- Mark scheme.doc (51.0 KB, 36 views)
13. AQA Style A2 physics past paper 1.doc (26.0 KB, 79 views)
14. (Original post by alevelstresss)
using E = (1/2)cV2

(1) 1600 = (1/2)cV2
(2) 400 = (1/2)c(V-2)2

4 = [cV2]/[c(V-2)2]
4(V-2)2 = V2
4V2 - 16V + 16 = V2
3V2 - 16V + 16 = 0
V = 4, V = 4/3

sub V = 4 into (1), 1600 = (1/2)16c
sub V = 4 into (2), 400 = (1/2)4c

1600 = 8c

c = 200
Thank you
15. (Original post by alevelstresss)
using E = (1/2)cV2

(1) 1600 = (1/2)cV2
(2) 400 = (1/2)c(V-2)2

4 = [cV2]/[c(V-2)2]
4(V-2)2 = V2
4V2 - 16V + 16 = V2
3V2 - 16V + 16 = 0
V = 4, V = 4/3

sub V = 4 into (1), 1600 = (1/2)16c
sub V = 4 into (2), 400 = (1/2)4c

1600 = 8c

c = 200
thats a daft amount of working for a 1 marker imo
16. (Original post by WillRose)
thats a daft amount of working for a 1 marker imo
yeah there must be a quicker way, but i did what i could

17. Does this always apply for kinetic energy?

Posted from TSR Mobile
18. (Original post by alevelstresss)
yeah there must be a quicker way, but i did what i could
not bashing you at all,just AQA
19. (Original post by alevelstresss)
yeah there must be a quicker way, but i did what i could
You have 45 ish minutes, so it's fine. I always spend longer on the MC anyway

Posted from TSR Mobile
20. (Original post by cmrol)
Can someone help me with question 19 on june 2014, https://60abffc9b401b1c0936e01291c15...%20Physics.pdf
I dont understand how you are meant to get 200, I got 600 when I did:

c = Q/V
1600/x = 400/(x-2)
1600x - 3200 = 400x
1200x = 3200
x = 8/3
c = 1600/(8/3)
c=600
Here's what I did, it's super long winded but it got there, there must be an easier way though!
21. (Original post by cmrol)
Can someone help me with question 19 on june 2014, https://60abffc9b401b1c0936e01291c15...%20Physics.pdf
I dont understand how you are meant to get 200, I got 600 when I did:

c = Q/V
1600/x = 400/(x-2)
1600x - 3200 = 400x
1200x = 3200
x = 8/3
c = 1600/(8/3)
c=600
You know e is proportional to v^2, so if you quarter energy, you must half the pd, so the original pd must be 4, as that's the only value that works in the situation. Just sub that into E=1/2CV^2.
22. do people do section a or b first?
23. What could a potential 6 marker about Induction be about?
24. (Original post by liverpool2044)
do people do section a or b first?
section b first because i can usually guess some of the MC if i am stretched for time

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: January 9, 2017
Today on TSR

### Luxury Dublin hotel bans ALL influencers

Discussions on TSR

• Latest
• ## See more of what you like on The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

• Poll
Useful resources

## Make your revision easier

Can you help? Study help unanswered threadsStudy Help rules and posting guidelinesLaTex guide for writing equations on TSR

## Groups associated with this forum:

View associated groups
Discussions on TSR

• Latest
• ## See more of what you like on The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

• The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE