Edexcel A-level Physics Paper 3 9PH0_03 14th June 2018 [Exam Discussion]

So, in being the mega procrastinator that I am, papers 1 and 2 didn't go great - since I left it so long to do any decent work for physics. As such, I need to do the best that I can for paper 3 on Thursday to try and redeem myself somewhat.

To those that are doing it: how are you revising for it? What would you say is the best way to cram as much as I can for this paper in such a short time?

Thanks in advance.

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Reply 1

poo man

Pretty much just learn all the practicals and do all 3 specimen papers as well as last year's paper, if got more time do some IAL unit 6 papers. Question: when calculating % uncertainty do you use the interval or half of the interval? Different mark scheme seem to use both. e.g. calculate %U of height when height = 5.23 cm. Some mark schemes do (0.01/5.23) x 100, while some do (0.005/5.23) x 100. I normally go the latter route but what would you do?

Reply 2

dwdw

Original post by poo man

from what i was told from my teacher basically edexcel messed up but in late 2017 they fixed their spec so that it should be half the smallest interval

Reply 3

poo man

Original post by dwdw

from what i was told from my teacher basically edexcel messed up but in late 2017 they fixed their spec so that it should be half the smallest interval

ah ok thanks alot

Reply 4

Teeenbe

Original post by poo man

Hmm, ok. Thanks for your response.

No clue about uncertainty, I'm afraid. Definitely need to cover that again. I see the other guy's got you covered tho, so all good.

Reply 5

megan.rowann

Original post by Teeenbe

Just make sure you have the core pracs down, I've spent all day today revising them. Definitely try last year's paper 3 as its the closest thing we have to the real thing. Good luck! x

Reply 6

Teeenbe

Original post by megan.rowann

Just make sure you have the core pracs down, I've spent all day today revising them. Definitely try last year's paper 3 as its the closest thing we have to the real thing. Good luck! x

Yeah, printed that and the 2017 unit 6 one from PMT as well, but am yet to do them. Gonna have a look through the core practicals and some of the definitions as well for practical vocab - pretty important to get that down as it caught everyone out last year! Hoping that it's not gonna be too horrible, but you know Edexcel and physics... A lot of things have been horrible recently actually, I've found. Thank you anyways and good luck to you too! x

Reply 7

D7E

Last year's paper 3 was pretty good ngl.

I'm still bricking it for tomorrow though ahaha

Reply 8

megan.rowann

Original post by Teeenbe

what do you mean by the practical definitions?x

Reply 9

Teeenbe

Original post by D7E

Last year's paper 3 was pretty good ngl.

I'm still bricking it for tomorrow though ahaha

For real tho hahaha

Original post by megan.rowann

what do you mean by the practical definitions?x

Referring to things like uncertainty, error, precision, accuracy, repeatability, reproducibility, true value, validity, resolution etc. x

Reply 10

megan.rowann

Original post by Teeenbe

For real tho hahaha

Referring to things like uncertainty, error, precision, accuracy, repeatability, reproducibility, true value, validity, resolution etc. x

Ahh cool thanks x

Reply 11

Teeenbe

Original post by megan.rowann

Ahh cool thanks x

No worries x

So, doing the 2017 paper 3 and the second question goes as follows:

2. A student carries out measurements to determine the density of glass. The student has 20 glass microscope slides available.
The approximate dimensions of one slide are shown.

<insert diagram of glass slide (regular cuboid)>

x =~ 75mm
y =~ 1mm
z =~ 25mm

(a) The density is calculated using the equation

density = mass/volume

Describe how the student can determine an accurate value for the density of the glass. Your answer should include the measuring instruments required. (4)

What I wrote for a means of calculating the volume was that you'd measure the dimensions x, y and z of the slide using a digital callipers. However, when I checked the mark scheme, it said this:

2(a)
- Use a micrometer to measure y and/or z (1)
- Use Vernier/digital calipers to measure x and/or z (1)

What I don't understand is why you'd have to use a micrometer for y and not be able to use the digital callipers for that as well?

Any help would be appreciated, please!

Reply 12

megan.rowann

Original post by Teeenbe

I think you can say to use digital calipers if you make it clear that you're only measuring one slide. I wasn't sure about that question either because digital calipers and micrometers have the same resolution.

Reply 13

Teeenbe

Original post by megan.rowann

Yeah, it says...

MP1 accept digital calipers for a single slide
Accept Vernier calipers if it is clear that the thickness of a number of slides is being measured.

so use a digital callipers for a single slide, as you say - so far, so good. But then it also says...

To award both MP1 & 2, x, y & z must all be referred to.

So all three dimensions need to be mentioned, but the mark scheme only has y as being found using a micrometer and not a digital callipers. Therefore, it would seem that they require you to write that you'd use both? But, again: I don't know what reason there would be for that because yeah, they're the same resolution :s-smilie: