OCR Physics A G482, Electrons, Waves and Photons, 25th May 2012

Reply 780

bencwbrown

11

Original post by mora11

virus virus virus virus :angry:

With my limited computer knowledge, I don't think .pdf files can be viruses, only if you open an executable file. Does your virus scanner actually say that it detects one or something?

(edited 11 years ago)

Reply 781

EmilyBea

1

would anyone be able to explain fundamental frequency, harmonics and the algebra bits that are involved in stationary/standing waves? a bit vague i know, but im struggling and neither of my text books are helpful! would be appreciated :smile:

Reply 782

bencwbrown

11

Original post by EmilyBea

would anyone be able to explain fundamental frequency, harmonics and the algebra bits that are involved in stationary/standing waves? a bit vague i know, but im struggling and neither of my text books are helpful! would be appreciated :smile:

Hi there I made 3 pictures on paint trying to describe each case of stationary waves for Closed end columns, Open end columns, and on Fixed Strings. I hope that they help, but if you still have any questions then I'll try and answer them later

closed end.png

Reply 783

EmilyBea

1

Original post by browb003

Hi there I made 3 pictures on paint trying to describe each case of stationary waves for Closed end columns, Open end columns, and on Fixed Strings. I hope that they help, but if you still have any questions then I'll try and answer them later

closed end.png

thank you so much!

Reply 784

Stevo F

18

Original post by browb003

With my limited computer knowledge, I don't think .pdf files can be viruses, only if you open an executable file. Does your virus scanner actually say that it detects one or something?

they CAN contain viruses, however, as this page shows you would have to ignore a message pretty much telling you that there is 1: http://www.enfocus.com/kb.php?id=981 I just downloaded one of them, it's safe, dont know about the rest of them yet :smile:

Reply 785

Toshiya

1

I keep JUST scraping As on past papers! This is what I did last year and got a C on the actual exam... not got long left to improve now!

Reply 786

Homeboy Hotel

10

I've got the Physics 1 book (specifically for OCR A) and the last part of Chapter 14 talks about deriving the formulas for resistor in series and parallel....uhh...do I need to know this?

I've read the spec and I can't really find it.

Reply 787

Stevo F

18

Original post by Homeboy Hotel

I've got the Physics 1 book (specifically for OCR A) and the last part of Chapter 14 talks about deriving the formulas for resistor in series and parallel....uhh...do I need to know this?

I've read the spec and I can't really find it.

no you don't

Reply 788

Stevo F

18

Original post by browb003

I've made booklets that compiles all the questions from the legacy papers on Electrons, Waves and Photons, so they are good for practice, but are unfortunately too large to upload to TSR:

Electricity and Circuits: http://www.datafilehost.com/download-613f326c.html
Electricity and Circuits Answers: http://www.datafilehost.com/download-b02fa244.html

Waves: http://www.datafilehost.com/download-0fe80efb.html
Waves Answers: http://www.datafilehost.com/download-b45a943f.html

Quantum: http://www.datafilehost.com/download-c58113a4.html
Quantum Answers: http://www.datafilehost.com/download-ee6996b1.html

Oh i never said thanks for this, its really useful :smile:

Reply 789

shorty.loves.angels

16

Original post by browb003

Probably through lots of practice, but it may help to write down all the values that are relevent to the components before starting the question.

Using this question as an example, perhaps you could write down I = 2.5A and that it applies to both the current going through the battery and the current goign through the internal resistance.

Or perhaps underline the key words (such as what components you need to consider in the question) as in part (c) you are told that the emf of the car battery is 12V, but you don't actually need it, where as you do need to know that the emf of the battery charger IS 14V, so perhaps underline battery to constantly remind yourself through the question?

Also check your units to make sure they are consistent (such as in this question, we were dealing with energy in Joules, but we had to get the energy by dealing with power in Joules/sec, so if you're stuck, see what the difference in the units is to perhaps give you a clue on what to do next i.e multiply by a time in seconds for this example)

(I'm just trying to come up with any type of advice that I can think of really, I'm sorry if it doesn't help :frown:

)

It does help honestly.

If I really understood it I'm sure I'd just be able to follow it through, but as I don't, I lose which I/ V/ R is relevant to what.

Hopefully, once I'm actually sat with the paper, I'll be able to annotate diagrams without copying it from the screen - this might help!

Honestly dreading this exam. Finding it more difficult than G484, and due to grade boundaries I only got a C in that :colonhash:

Reply 790

Emissionspectra

11

Original post by shorty.loves.angels

It does help honestly.

If I really understood it I'm sure I'd just be able to follow it through, but as I don't, I lose which I/ V/ R is relevant to what.

Hopefully, once I'm actually sat with the paper, I'll be able to annotate diagrams without copying it from the screen - this might help!

Honestly dreading this exam. Finding it more difficult than G484, and due to grade boundaries I only got a C in that :colonhash:

What bits do you find hard?

Reply 791

shorty.loves.angels

16

Original post by Emissionspectra

What bits do you find hard?

Mainly following the circuits question. Takes me so long to really know what to do that as I go through I forget what's what, and it just doesn't piece together very well in my head; I often use the wrong values etc.

Erm, I get some wave questions wrong too but I think that's more being careless. Most other parts I'm generally ok with. But I do find that no matter how many papers you go through, all the questions are different, like, I never really get to practise my understanding of one scenario because there's something different to learn. I guess I just haven't grasped all the topic as well as I'd have liked.

Oddly, I wasn't finding G485 too bad :s

EDIT to add: I might even write down all the rules/ laws of circuits and keep referring to them when answering questions, so as to keep on track with them and keep reminding me of them.

(edited 11 years ago)

Reply 792

Exotica

I was wondering if anyone has any idea of the highest the grade boundary it has ever been for an A on this paper? And which year?

Reply 793

TwinAz

Original post by browb003

I've made booklets that compiles all the questions from the legacy papers on Electrons, Waves and Photons, so they are good for practice, but are unfortunately too large to upload to TSR:

Electricity and Circuits: http://www.datafilehost.com/download-613f326c.html
Electricity and Circuits Answers: http://www.datafilehost.com/download-b02fa244.html

Waves: http://www.datafilehost.com/download-0fe80efb.html
Waves Answers: http://www.datafilehost.com/download-b45a943f.html

Quantum: http://www.datafilehost.com/download-c58113a4.html
Quantum Answers: http://www.datafilehost.com/download-ee6996b1.html

Thankyou for these!

Reply 794

Gkt1378312870

13

Original post by browb003

I've made booklets that compiles all the questions from the legacy papers on Electrons, Waves and Photons, so they are good for practice, but are unfortunately too large to upload to TSR:

Electricity and Circuits: http://www.datafilehost.com/download-613f326c.html
Electricity and Circuits Answers: http://www.datafilehost.com/download-b02fa244.html

Waves: http://www.datafilehost.com/download-0fe80efb.html
Waves Answers: http://www.datafilehost.com/download-b45a943f.html

Quantum: http://www.datafilehost.com/download-c58113a4.html
Quantum Answers: http://www.datafilehost.com/download-ee6996b1.html

You are an absolute boss! Thank you very much mate :biggrin:

Now to get through like a 1000 questions in less than 2 days hahaha

Reply 795

ViralRiver

16

If you learn well from flashcards, I made some when I took the physics exams during my A levels. Problem is, I can't remember which ones apply to which exams, but you can work that out. I've linked to them below :smile:

Reply 796

shorty.loves.angels

16

Original post by ViralRiver

If you learn well from flashcards, I made some when I took the physics exams during my A levels. Problem is, I can't remember which ones apply to which exams, but you can work that out. I've linked to them below :smile:

As I only got round to making flashcards for about 20% of G482, these are fantastic. Thank you!

Reply 797

enlighten25

does anyone know exactly which experiments we need to remember for this exam, you know those 4-12 mark bits i hate. i think one of them is something to do with the diffraction of waves, youngs double slit exp, etc.
does anyone know how to draw the diagram for qu 4.c.ii. jan 2012 dont have the paper so cnat upload it asks
describe how you would demonstrate that a sound wave of wavelength 0.10m emitted from a loudspeaker can be diffracted(4marks)
i know that the width of the gap is comparable (same) as the wavelength(0.10m)
but thats about it, any help much appreciated, thanks.

Reply 798

enlighten25

hey
i really don't get 1)c)ii) can someone draw for me what the graph should look like its for 2marks
also 1)d)iii how to work out current(3marks) looking at the ms its not clear where the voltage 240V came from for the 'alternative set of lamps'
also 2)c)iii about wroking out the % energy supplied? dont get that??
and finally... how do you know the wavelenght of the stationary wave is lambda over 2??? on 5)b)iv.? and just in general i dont get how you know whats the 1st 2nd or 3rd harmonic and how do you know which wavelength to use for stationary waves when using the formula v=flambda given using either wavelenght=lambda/2 or 3/2 lambda or one lambda??
so confused someone please help before tomorrow and whats the difference between external resistance R and internal resistance r i don't know when to use which is which finally dont get difference between p.d , voltage and e..m.f aren't they alll the same why not? sorry for so many qus otherwise i'll not do well on this :smile:

Reply 799

enlighten25