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AQA Physics Unit 1 PHYA1 20th May 2013

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True. Not sure why it was 2 marks then, but at least I got em.

This confused me as well. Looking through the past papers + specimen, the only similar question I can find is from May 2011, Question 6cii), "Draw a line on the graph ... that shows the results obtained from a cell with the same emf but negligible internal resistance...", which was only worth 1 mark, so I'm not sure where the other mark comes from either.

Reply 1441

tetra-s

Original post by Zakee

It's only one horizontal line as a direct current doesn't reverse direction remember. It just flows in one conventional direction. If it were two horizontal lines, that would mean a current is flowing simultaneously in both directions which, well, is baffling.

That does make sense, as rms value means you have squared all the voltage values to not get them negative.

I must have got confused and thought you could reverse the current like you can in a circuit. Lucky I didn't draw it :P

Reply 1442

Super Dica

Hello guys... who sat for the unit 1 aqa physics today. 20/05/2013

Reply 1443

Zakee

Original post by GeneralOJB

True. Not sure why it was 2 marks then, but at least I got em.

I presume it being a straight line (one mark) as a constant voltage. Also realizing the DC is actually the RMS value (so drawing along the 45/45.3V or your RMS value) - second mark.

For example, someone may draw a straight line but in the wrong place (one mark). Or may draw an incomplete line for the DC at 45.3/sinusoidal wave starting at 45.3V.

all of us! :biggrin:

Can somebody please tell me how many marks each part was worth on questions 6 and 7? i can't remember for the life of me but I know I have some bits rights and others wrong so I wanna know how many marks I've lost :P

Reply 1446

Xiomara

Original post by Khenir

My method was this:

0.75 = 5000*I
so I = (0.75/5000)

I didn't think properly and had this:

5.25 = I*(5000 + R)

and then I realised that I*5000 was 0.75 (since I'd done it earlier DUH).

so 4.5 = IR = (1.5*10^-4)*R

so R= (4.5)/(1.5*10^-4) = 30,000.

Thank you

Reply 1447

Qari

Think only marks I lost on question 7 were for the LDR, 2 marks gone down the drain. Hopefully I get 6 out of 6 on question 3.
The minute I saw it was a hadron lepton question , I raised my head and thanked Allah(God)

Reply 1448

StalkeR47

Original post by Qari

Ma Sha Allah! :smile:

But the thing is, since the question was easy most people did pretty well. And therefore as a result, grade boundary might rise. :frown:

Reply 1449

Qari

Original post by StalkeR47

Ma Sha Allah! :smile:

But the thing is, since the question was easy most people did pretty well. And therefore as a result, grade boundary might rise. :frown:

It depends though, I mean maybe not everyone is strentgh is Hadrons & Leptons, but I know what you mean. I'm confident that I got 80% of the Maths questions right.
BTW for question 1 most people got 4.0x10^6 but I got 3.99x10^6 would I get a mark?

Reply 1450

ac3xx

Original post by Declan_Brennan

6ai) pd of battery - 1 mark
ii) pd of R - 1 mark
iii) Current through 2ohm resistor - 1 mark
iv) Current through R - 1 mark
v) Resistance of R - 1 mark
vi) Overall resistance - 2 marks
b) Table of power values - 3 marks
c) Proof of energy conservation - 2 marks
(Total 12)

7ai) Current in circuit - 1 mark
ii) Voltmeter reading - 1 mark
b) Effect on Voltmeter reading if intensity of light striking LDR increases - 2 marks
c) Resistance of the variable resistor - 3 marks
(Total 7)

Reply 1451

TheSnail

Just unit 2 to focus on now!

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

Reply 1452

ac3xx

Original post by Qari

I put 3.99x10^6 - it's 3 s.f. and you aren't being assessed for significant questions on that question so you should get the marks.

Reply 1453

StalkeR47

Original post by Qari

I think you should do since the question did not stated the accuracy of the sig fig. :smile:

Reply 1454

swagadon

Original post by Qari

i got the same as you, i dont think they care about the significant figures unless they tell you so

Reply 1455

marumakan

Original post by Kayakayakaya

question 4, about the frequency being reduced, surely this has no effect unless the frequency is below the threshold frequency?

I agree. I said no effect because intensity doesnot affect what ver the question says?

Reply 1456

FMEC1996

Just looking to clarify a few things:

2b) I wrote that the photon is virtual and cannot be detected whereas the weak boson can.

2c) I wrote about the particle as a whole, saying that the charge from a proton (+1) is preserved with the charge of the positron, would that be okay?

4cii) I wrote that the kinetic energy of the electrons would decrease until it was below the threshold frequency where no electrons would then be emitted?

6b) For the values in the table is it okay that I rounded to 1 dp?

7b) If i accidentally read the question as the light intensity decreasing but explained it correctly, would what happen then?

Thanks