AQA Physics PHYA4 - Thursday 11th June 2015 [Exam Discussion Thread]

I'll start looking into it next week when we go over more in class (although I think he said he'd give us our proper dates tomorrow)

Ooh exciting We've just been a presentation task on different kinds of EM spectra telescopes. I'm doing gamma telescopes - do you know if you have to recall much about the different types? Or is this another one of my teacher's annoying off-syllabus tasks? Aha.


Posted from TSR Mobile

As far as I know (and as far as I have in my notes), there's a bare minimum about other telescopes plus a lot on optical and radio. So reflectors/refractors and radio telescopes in detail, then the fact that infrared and ultraviolet are basically the same as optical with a CCD attached, and as X rays are usually absorbed or go through they use grazing mirrors to gradually focus them onto a detector. Can't remember anything about gamma but I would imagine the same as X rays because it's the same problem. Also that how perfect the dish needs to be depends on wavelength.

What experiments have you had to do for mock EMPAs?

Ah right, thanks so much for the detailed info. It's so annoying not knowing how in depth I should be absorbing the content!

Both of our mocks had things to do with capacitors and pendulums so wink wink nudge nudge aha.


Posted from TSR Mobile

Seeing as we've finished I'm fairly sure our teacher hasn't had time to get too off syllabus

I guess those are about the only topics that have practicals? You can't do any on astro, not on nuclear really, thermal is just about possible but unlikely I think, all the fields stuff is out I think? Seeing as there have to be two experiments I guess it's capacitors and simple harmonic motion every year!

Aha! Don't worry, as far as I can tell ISAs are internally marked by your teachers/assessors, right?
EMPA = Externally Marked Practical Assessment. As far as I can tell, despite the experiments being slightly different, the EMPA is externally marked. We do two practicals and record results/plot a graph in section A, then answer theory questions related to both practicals in section B. How similar is that to the ISA, (minus the external marking)?

Why is the answer to question 22 "C?"
How would you calculate it? :/

http://filestore.aqa.org.uk/subjects/AQA-PHYA4-1-QP-JAN13.PDF

Pretty similar actually. We do one experiment and one paper after it - answer questions on working out gradients percentage errors and stuff like that. A lot of centres cheat though as it is internally marked so the grade boundaries are ridiculously high - it works out about 43/50 for a B grade which makes it incredibly difficult for centres that don't bend the rules.

Posted from TSR Mobile

Excuse the poorly written explanation - I wish I could type Greek letters on my phone...

A general equation for the emf, E, is E=BANw(sin(2π)*f*t)

They've given you:

ε = 20 sin (100 πt)

The maximum value of that equation is when sin(100πt) = 1 (as the emf varies sinusoidally and the max value of sine is 1).

This means the peak emf = 20*1 = 20V

Comparing the general equation with the one given in the question, 100 πt = 2 πft
Dividing by 2 πt on both sides gives f=50Hz




Posted from TSR Mobile

Aha, still pretty jealous about that yeah it does seem that way! They are fairly nice experiments though so I wouldn't complain if we got them that said, I felt okay after last year's practical and got a C...


Posted from TSR Mobile

Thank you! That makes so much more sense now.
Aha don't worry, the explanation couldn't have been better.
I wish I could see the link between equations as well as you can!

I think the practicals will usually go alright, it's more the question paper section that's the problem :/ I just hope it doesn't let me down too much!

So, we had a mock on this not long ago and I did terrible. I got 267/300 in my AS physics last year and AAAA overall in my AS exams, but in the mocks (june 14 papers) I got an A* in phy5 and an E in phy4... Help! What do I do? I got As/A*s in my maths and further maths mocks and then an E in the middle of my results. Any advice? I'm really panicking because my uni offer is AAA.


Posted from TSR Mobile

So, we had a mock on this not long ago and I did terrible. I got 267/300 in my AS physics last year and AAAA overall in my AS exams, but in the mocks (june 14 papers) I got an A* in phy5 and an E in phy4... Help! What do I do? I got As/A*s in my maths and further maths mocks and then an E in the middle of my results. Any advice? I'm really panicking because my uni offer is AAA.


Posted from TSR Mobile

I need to learn how to draw a proper graph apparently. My paper had "poor graph" scrawled all over it last year hahaha!


Posted from TSR Mobile

The main thing is not to let that daunt you, but motivate you! You have plenty of time to revise and go over the paper. June 2014 was not an easy paper at all!


Posted from TSR Mobile

The unit 4 paper (particularly June 14!) is pretty horrible with that multiple choice section. Go over the paper and look for what tripped you up as a starting point, this should give you some things you need to work on. Practice practice practice the multiple choice section and keep a careful eye on timings!