Post by: paulsterio on December 27, 2011, 06:10:07 pm
A little bit about myself first, I graduated from year 12 in 2011 with a study score of 46 in Physics.
Scored: 159/180 for Unit 3 and 179/180 for Unit 4 in Exams
Physics is extremely competitive, so unlike subjects like Biology, where you can afford to lose about 4 marks per exam and still get a 50, the margin for physics is probably around 1 mark per exam, maybe 3 marks in total if you have really strong SACs (i.e. 100/100 for SACs). You could even get away with losing 4 marks in total with 100% SACs (Thushan got 172/180 for Unit 3 and pulled off a 50). So physics, therefore, is really about how to minimise errors and not lose marks on explanations. Physics examiners are probably a little bit more relaxed than say Biology examiners in that your explanations need to be logical and mathematical rather than worded in a certain way. If you answer makes sense, then you are on track to gain full marks for that part.
Alrighty, so let's start off with Unit 3
Unit 3 consists of two core areas and one detailed study. The core areas are Motion and Electronics/Photonics. The detailed studies are Relativity, Structures/Materials and Further Electronics.
I completed Further Electronics in Unit 3 and was really dogged out by a really hard Further Electronics exam that lost me a lot of marks. You don't really have a choice here because your school picks the study for you, although I do suggest that you learn an extra detailed study, make sure you are "exam quality" for the extra one you learn though, then you can make a choice during reading time. That's what I did for Unit 4, and it was much better, detailed studies are relatively easy (usually) compared to the core work.
AOS 1 - Motion
Motion is probably the most difficult area in Unit 3 physics. There's not many explanations, but there's a lot of calculations.
In terms of explanations, make sure you can explain simple things such as:
- Conservation of Energy
- Conservation of Momentum
- Why we can accelerate more if we are on an banked road compared to a flat road
- Elastic and inelastic collisions
- Apparent weightlessness compared to true weightlessness
- Other things, which I'll add as soon as I remember
If you choose to do it using first principles, you will do things such as this:
- Find the maximum acceleration on a banked curve? You will resolve the forces and find the maximum friction force...etc and arrive at the answer
- Find the acceleration down an inclined plane? You will resolve parallel to the plane and get F = mgsin(theta) -> a = gsin(theta)
For example:
- Projectile motion is "quadratic" so you can technically find the flight time by solving the general case of the quadratic equation
- Similarly, projectile motion can be solved by using formulae as well
AOS 2 - Electronics and Photonics
This is probably two distinct studies in one. Electronics is relatively easy and most will probably find it quite easy. You only really have to know the basic electronics formulae such as V = IR, P = VI and associated power formulae, you will have to understand voltage dividers, which can be solved using the formula found in textbooks or by first principles (finding the current), you will also have to know about amplifiers. Most of the calculations here are easy, but circuit analysis can be quite tough sometimes, especially when diodes are involved, but stick to your principle of "Parallel = Same Voltage" and "Series = Same Current" and you should be able to knock them down. Now over to the photonics section, this is just really explanations, you have to understand about modulation and associated terms as well as probably how to transfer these principles to the transfer of information via fibre optic systems. You'll also have to analyse circuits with added photonic devices, i.e. LDRs, LEDs, LDs, Photodiodes.
In terms of explanations, make sure you can explain these key concepts:
- Modulation/Demodulation
- Terms to do with Modulation - Carrier wave, signal wave...etc
- Whether an increase in light (or temperature) or whatever will cause in an increase in voltage across a particular resistor in a Voltage Divider
- Explain whether a switching circuit (e.g. air-con/heater) is designed properly (voltage divider) and if not, why?
- Explain how data is transmitted in a photonic system
- Clipping, distortion, cut-off and saturation of amplifiers
AOS 3 - Detailed Study
Relativity (By Laseredd)
So, in my opinion, the special relativity detailed study was the most interesting part of Unit 3, if not the entire course. You're exposed to ideas that are fairly out there - coming across things like "two events that occur simultaneously in different places in one frame of reference may occur at different times in another frame of reference" will probably make you think :o . But that shouldn't be a problem, once you get your head around the key concepts, it's actually seems quite simple and in a weird way, almost "intuitive".
Without a doubt, the most important thing about this detailed study are the concepts. You need to realise that there are a few key principles to the ideas and that the rest are just consequences. The meat of special relativity are the two postulates, which always seem to be differently worded everywhere you read (but the ideas always stays the same). You need to thoroughly understand what these two postulates are. You need to spend time getting your head around the idea of reference frames. You need to understand the consequences of special relativity (the ones that are covered in VCE Physics anyway): time dilation, length contraction, simultaneity, relativistic mass/momentum, mass-energy equivalence (not a complete list).
There's other stuff I've neglected to mention: the history aspect of the study, where you are introduced to how the theory came to be developed (Newton/Galileo, the "aether", Michelson-Morley experiment, what Maxwell discovered etc.). That stuff is fairly straight forward, but still something that needs to be understood (almost always will there be a question about the Michelson-Morley experiment).
Why am I going on about understanding the concepts so much? Besides from being a very theory heavy area of study, the calculation part is quite simple - but it depends on being able to differentiate between reference frames etc. So all that complicated stuff boils down to 12 or 13 pretty simple questions. The detailed studies are multiple choice, which allows you to quickly eliminate a few answers. This is handy, since you will probably only allocate 20 - 25 minutes for the detailed study. For most questions, this is very easy in relativity, since if you know your theory you can tell that one of the given answers is talking about the wrong reference frame or that it violates one of the postulates etc.
About the calculations, it's mostly dealing with subbing in values into simple equations. This goes for everything else in VCE Physics, but ensure you know how to use your scientific calculator well. However, you do need to do a lot of transposing (may be a good idea to pre-transpose a few of the equations for your cheat sheet), so you should be able to quickly transpose this:
Oh and also, you don't need to show working for the detailed studies, but you're given enough space to do calculations on the page. It's definitely worth doing some amount of working in case you come back to check over your work.
Structures and Materials
Now I'm gonna need some assistance here, anyone who has done these two detailed studies and want to write a guide, feel free to, I'll add it onto here :)
Further Electronics
This is an alright detailed study, not too hard, not too easy, it uses a lot of skills which have already been learnt from the other sections. It's centred around rectifying an AC voltage into smooth, stable DC. You'll have to be familiar with a bridge rectifier, capacitor, zener diode (and also IC voltage regulator). Essentially you will also have to know a little bit about CROs and how to read their outputs. You'll also have to know what the output of a bridge rectifier would look like (kind of like an absolute sine function), output after a capacitor as well as output after the zener diode. You should be able to calculate time constants and ripple voltage from the standard formulae. All of the questions are Multiple Choice which should make it a little easier or harder depending on whether you like MC.
Unit 3 Exam Advice
- You should be aiming to do about 20 practice exams for physics
- Note your mistakes and don't make them again
- If you're aiming for a 45+ study score, you should be aiming to really finish the whole paper in about 1 hour and 15 minutes.
- You should also be getting all numerical (calculation) questions right as well as getting the explain questions mostly correct.
- You should aim to really get 100% on the Detailed Study, this means that a mark lost due to an incomplete explanation will not be so costly
- Remember to reason using a formula during explanations, it usually works and it's an easy way to explain a lot of concepts.
- Double check numerical questions.
- Write your formula sheet early on in the year, and improve on it whilst you do practice exams, include what you don't know, don't waste space including what you already know and won't be referring to in the exam.
- Work out a specific order and stick to it, (my order was Motion, Electronics, Detailed Study)
- Make sure your calculator has battery, change it before the exam if you're pedantic.
- Remember to bring a pencil for the Multiple Choice
- When doing practice exams, don't rush, give yourself 1 hour and 15 minutes, don't try to finish it in 45 minutes if you're making careless errors.
- Make "model answers" for typical exam explain questions
Post by: paulsterio on December 27, 2011, 06:11:38 pm
Similar to Unit 3, the two core area of studies will be different. Electric power will mostly be mathematical questions with few explanations whilst Light/Matter will be mostly explanation with a few mathematical questions. The three detailed studies for Unit 4 are Synchrotron, Photonics and Sound. I did both Photonics and Sound, but completed Photonics in the Exam as it was far easier (in my opinion and judgement).
AOS 1 - Electric Power
This is the most difficult area of study in all of Year 12 physics, I found it difficult in that the concepts weren't too bad, but some of it was just downright confusing. You should be familiar with the formulae, all of which are relatively easy to apply. The challenge in Electric Power comes from concepts involved. You'll have to have a good understanding of the hand rules, the Grip Rule and Slap Rules (or other variations which you might like to use). Motors and the like are all relatively easy. You also have to understand the concepts of magnetic flux and induced voltage. You generally have to be able to explain the following things:
- Draw magnetic field lines
- Difference between slip rings and a split ring commutator
- Where you would use slip rings or a split ring commutator
- Explain why you want to use a high voltage for transmission
- Explain why transformers only work with AC (explain it using change in flux = induced voltage, DC produces no change in flux)
- Explain ways to reduce power loss during transmission
- Draw a graph of voltage given the graph of flux
- Draw a graph given the rotational period (and other info) of a rotating loop
AOS 2 - Light and Matter
To sum up Light and Matter, it's extremely abstract. There's very little maths, although you have to be able to calculate things such as the Work Function, or the energy required to remove an electron from a certain metal (and other photoelectric effect type calculations). You also have to be able to draw graphs for the photoelectric effect as well as interpret energy level diagrams for an atom (or draw them). You might also have to draw standing waves around an atom to show how electrons moved. Then there's calculation of momentum of a photon or the de Broglie wavelength of an animate particle. You will have to be able to explain the following things:
Post by: paulsterio on December 27, 2011, 06:12:21 pm
Post by: Aurelian on December 27, 2011, 06:20:06 pm
...although I do suggest that you learn an extra detailed study, make sure you are "exam quality" for the extra one you learn though, then you can make a choice during reading time. That's what I did for Unit 4, and it was much better, detailed studies are relatively easy (usually) compared to the core work.
This is really unnecessary... I would strongly recommend against this D=
Post by: Hellrocks on December 27, 2011, 06:54:24 pm
Post by: paulsterio on December 27, 2011, 07:08:54 pm
Post by: Lasercookie on December 27, 2011, 08:04:26 pm
Something that you didn't explicitly mention, which is probably pretty obvious (but still worth mentioning nonetheless), is that while you can use short-cut formulae, it's a risk if you don't thoroughly understand the "first principles" method or if you don't know the limitations of the formulae (for examples, those projectile motion ones are the really obvious case here regarding limitations).
Learning the "first principles" method is probably the way you'd go for learning the concept in the first place. I'd also emphasise that it's pretty much always worth spending the time to look at some form of derivation for every formula you come across in Unit 3/4 Physics. I found it helped me a lot for understanding what a formula was going on about etc.
Post by: Deceitful Wings on December 27, 2011, 08:08:36 pm
How many marks can you lose to afford to get a study score above 45?
Post by: paulsterio on December 27, 2011, 08:13:19 pm
Something that you didn't explicitly mention, which is probably pretty obvious (but still worth mentioning nonetheless), is that while you can use short-cut formulae, it's a risk if you don't thoroughly understand the "first principles" method or if you don't know the limitations of the formulae (for examples, those projectile motion ones are the really obvious case here regarding limitations).
Hmm, that's true actually, I guess I never really got my head around some things such as banked curves, but I just made up some custom formulae and it's always worked for me, but you do raise a really good point, you do have to understand what the formula means and how it's derived.
This is really helpful advice, thanks for this post :P
How many marks can you lose to afford to get a study score above 45?
You're welcome :)
Well I got 159/180 and 179/180, so I lost 22 marks, and when you halve that, it's 11 marks, so I guess you could probably lose around that much and get a 45, I had 100/100 for SACs, however. So that would have also played a part, but I think 10 marks lost in total should be ok for a 45+
Post by: max payne on December 27, 2011, 08:58:02 pm
correct me if i'm wrong but i believe 159 and 179 is better than 169 and 169Assuming that grades are not linearly distributed then thats probably true...although I'm not sure
Post by: paulsterio on December 27, 2011, 09:25:59 pm
Post by: pi on December 28, 2011, 10:28:40 am
Post by: Lasercookie on December 28, 2011, 10:30:45 am
AOS 3 - Detailed Study
Relativity
Structures and Materials
Now I'm gonna need some assistance here, anyone who has done these two detailed studies and want to write a guide, feel free to, I'll add it onto here :)
Detailed Study 1: Einstein's Special Relativity
So, in my opinion, the special relativity detailed study was the most interesting part of Unit 3, if not the entire course. You're exposed to ideas that are fairly out there - coming across things like "two events that occur simultaneously in different places in one frame of reference may occur at different times in another frame of reference" will probably make you think :o. But that shouldn't be a problem, once you get your head around the key concepts, it's actually seems quite simple and in a weird way, almost "intuitive".
Without a doubt, the most important thing about this detailed study are the concepts. You need to realise that there are a few key principles to the ideas and that the rest are just consequences. The meat of special relativity are the two postulates, which always seem to be differently worded everywhere you read (but the ideas always stays the same). You need to thoroughly understand what these two postulates are. You need to spend time getting your head around the idea of reference frames. You need to understand the consequences of special relativity (the ones that are covered in VCE Physics anyway): time dilation, length contraction, simultaneity, relativistic mass/momentum, mass-energy equivalence (not a complete list).
There's other stuff I've neglected to mention: the history aspect of the study, where you are introduced to how the theory came to be developed (Newton/Galileo, the "aether", Michelson-Morley experiment, what Maxwell discovered etc.). That stuff is fairly straight forward, but still something that needs to be understood (almost always will there be a question about the Michelson-Morley experiment).
Why am I going on about understanding the concepts so much? Besides from being a very theory heavy area of study, the calculation part is quite simple - but it depends on being able to differentiate between reference frames etc. So all that complicated stuff boils down to 12 or 13 pretty simple questions. The detailed studies are multiple choice, which allows you to quickly eliminate a few answers. This is handy, since you will probably only allocate 20 - 25 minutes for the detailed study. For most questions, this is very easy in relativity, since if you know your theory you can tell that one of the given answers is talking about the wrong reference frame or that it violates one of the postulates etc.
About the calculations, it's mostly dealing with subbing in values into simple equations. This goes for everything else in VCE Physics, but ensure you know how to use your scientific calculator well. However, you do need to do a lot of transposing (may be a good idea to pre-transpose a few of the equations for your cheat sheet), so you should be able to quickly transpose this:
Oh and also, you don't need to show working for the detailed studies, but you're given enough space to do calculations on the page. It's definitely worth doing some amount of working in case you come back to check over your work.
Post by: paulsterio on December 31, 2011, 12:10:59 am
Post by: b^3 on December 31, 2011, 12:14:30 am
I guess this got superseded by Samad's guide ;D oh well :) I'm nearly done so I'll finish off Unit 4 tomorrowDW paul this got added to the resource thread aswell.
Post by: Phy124 on December 31, 2011, 01:21:57 am
I guess this got superseded by Samad's guide ;D oh well :) I'm nearly done so I'll finish off Unit 4 tomorrowI think it is good to see things from different perspectives. I read both guides and I would hope physics newcomers will too.
Post by: Kanon on January 03, 2012, 03:22:04 am
I was just wondering if you could explain what reasoning with first principles is, I've given it a quick wiki and from my interpretation (which seems wrong, haha) it involves making assumptions based on the situation where a law applies? As for the detailed studies, does Further Electronics and Special Relativity get marked with any consideration on the difficulty of the subject, eg, getting 10/20 for Special Relativity is the same as getting a 15/20 in Further Electronics? We've got a straight from Uni Mechanical Engineer teaching us Physics through some weird program, and it seems like he's giving us the option on what to study, so I'm considering voting Special Relativity because our schools maths is probably not at the same level as the rest of the state, and with considerations that might help out abit, does that seem logical to you?
Post by: Lasercookie on January 03, 2012, 12:12:47 pm
Extremely useful guide Paul :)What I assumed what Paul meant by the term was to do things without using shortcut formulas i.e. start off with the original formula and work down from there. I'll type up an example of what I think Paul meant soon (picking out which question to use).
I was just wondering if you could explain what reasoning with first principles is, I've given it a quick wiki and from my interpretation (which seems wrong, haha) it involves making assumptions based on the situation where a law applies?
Quote
As for the detailed studies, does Further Electronics and Special Relativity get marked with any consideration on the difficulty of the subject, eg, getting 10/20 for Special Relativity is the same as getting a 15/20 in Further Electronics?No, I don't believe they moderate the detailed studies.
Quote
We've got a straight from Uni Mechanical Engineer teaching us Physics through some weird program, and it seems like he's giving us the option on what to study, so I'm considering voting Special Relativity because our schools maths is probably not at the same level as the rest of the state, and with considerations that might help out abit, does that seem logical to you?I'm not entirely sure what you mean by maths and level with the rest of the state, but (extreme bias) Special Relativity was pure awesome fun to learn and I strongly recommend it :P
Post by: Lasercookie on January 03, 2012, 12:38:30 pm
Extremely useful guide Paul :)What I assumed what Paul meant by the term was to do things without using shortcut formulas i.e. start off with the original formula and work down from there. I'll type up an example of what I think Paul meant soon (picking out which question to use).
I was just wondering if you could explain what reasoning with first principles is, I've given it a quick wiki and from my interpretation (which seems wrong, haha) it involves making assumptions based on the situation where a law applies?
Question 9 - VCAA 2011 Exam 1
Using short-cut formulae that you already had on your cheatsheet:
Alternatively:
You would know that at A the centripetal force is due to the weight of the car and the normal. You also know that the normal force must be greater than 0, otherwise the car would fall off the tracks. So the minimum speed for the car, is when the normal force is equal to 0.
So you have:
Solve for v
Since N = 0:
(oh, I had forgotten that this method of working out leads back to that formula lol)
Then continue as above to get the answer.
Anyway, I'm not sure if that's the best example, but you can see that the second method of working out is a bit more thorough.
Post by: paulsterio on January 03, 2012, 01:00:18 pm
In terms of what Laseredd is saying, if I were doing it with first principles, I would probably just sub everything in at this step:
I would say, N = 0
so then you essentially have
then essentially you solve numerically for v
Post by: Phy124 on January 03, 2012, 01:29:05 pm
Extremely useful guide Paul :)The detailed studies are not weighted and at times this can be quite unfair. As paul has previously mentioned the further electronics detailed study had some very challenging questions in the 2011 Exam, which very few students answered correctly. The same can be said for Einstein's relativity.
I was just wondering if you could explain what reasoning with first principles is, I've given it a quick wiki and from my interpretation (which seems wrong, haha) it involves making assumptions based on the situation where a law applies? As for the detailed studies, does Further Electronics and Special Relativity get marked with any consideration on the difficulty of the subject, eg, getting 10/20 for Special Relativity is the same as getting a 15/20 in Further Electronics? We've got a straight from Uni Mechanical Engineer teaching us Physics through some weird program, and it seems like he's giving us the option on what to study, so I'm considering voting Special Relativity because our schools maths is probably not at the same level as the rest of the state, and with considerations that might help out abit, does that seem logical to you?
Although, VCAA may make this year's questions for these detailed studies easier, I think that structures and materials is the best detailed study to chose for minimizing marks lost. It seemed to me that their wasn't really a broad spectrum of questions that could be provided for S&M. In most of the practice Exams I did, the only things that changed were units on graphs - very little places a good student can go wrong.
In summary, as the current syllabus is in existence for a longer periods, VCAA will be looking for harder questions that students won't have seen before, which I believe would be quite hard to do for Structures & Materials as the material is quite limited, unlike the other two.
For basis, in the 2011 Exam, the amount of questions answered correctly by 50% or less students is below:
Structures and materials - 2
Einstein's relativity - 6
Further electronics - 5
Also, 2010 Exam:
Structures and materials - 1
Einstein's relativity - 4
Further electronics - 3
Only my opinion, though.
Post by: Kanon on January 04, 2012, 03:15:38 am
I'm probably going to try and play it safe and vote for Sound and Materials, as it seems like if there's no further accreditation towards SR or FE. Aswell as Phy mentioned, it'd be more difficult to find harder questions for what I think is the last year of the study design for Physics. :)
Post by: Lasercookie on January 04, 2012, 01:35:23 pm
Aswell as Phy mentioned, it'd be more difficult to find harder questions for what I think is the last year of the study design for Physics. :)The current study design ends on 31 December 2014. I think it was originally going to end sometime earlier, but they extended it some time back. My guess is that the next study design is going to be the national curriculum study design (why else would they extend it to 2014?).
Post by: paulsterio on January 08, 2012, 12:15:16 am
Post by: Lasercookie on January 08, 2012, 12:41:49 am
I don't think there's a national curriculum for Y11-12?There's definitely a national curriculum for year 11/12. But anyway, that was just my stab in the dark guess at to why they would have extended the accreditation period. They might have extended it for some other reason.
They are developing on the year 10 and under curriculum first I know. The senior secondary stuff is in initial consultation stages.
You might be interested in these documents, it provides a bit more detail: http://www.acara.edu.au/verve/_resources/Information_Sheet_Australian_Curriculum_development_timelines.pdf
http://www.acara.edu.au/verve/_resources/Senior_Secondary_Info_Sheet_-_KW.pdf
Oh, I just noticed this paragraph, which confirms (sort of) my guess:
Quote from: http://www.acara.edu.au/verve/_resources/Senior_Secondary_Info_Sheet_-_KW.pdf
The senior secondary timelines for english, mathematics, science and history are based on the assumption that the Australian Curriculum in these areas should be ready for Ministerial endorsement by October 2012 and available for implementation from
2014, building on the implementation of and learning from the Foundation to Year 10 curriculum in these areas. This timeline provides for the curriculum to be available for one year prior to implementation to allow for implementation and professional learning, planning and support. An implementation timeline is yet to be determined for senior secondary curriculum.
So they give the date of 2014 for the senior secondary curriculum to be ready for implementation, which fits in with VCAA's extension of physics, methods, specialist, chemistry, english etc. to 2014.
That last sentence doesn't sound too encouraging though. (and I think implementation of Foundation to Year 10 has been delayed as well).
Post by: FlorianK on July 21, 2012, 10:21:18 pm
Post by: Lasercookie on July 21, 2012, 10:25:57 pm
Why are your exam scores out of 180?VCAA exams are marked by two assessors, and the marks get added together - well something along the lines of that, don't quote me on the adding the two marks together thing, I'm not actually sure on the details e.g. there's some more processes where they get in a third assessor if the marks from each assessor have a significant difference (I don't know how the marks are calculated then).
Post by: Hutchoo on July 22, 2012, 12:21:27 am
Why are your exam scores out of 180?VCAA exams are marked by two assessors, and the marks get added together - well something along the lines of that, don't quote me on the adding the two marks together thing, I'm not actually sure on the details e.g. there's some more processes where they get in a third assessor if the marks from each assessor have a significant difference (I don't know how the marks are calculated then).
I believe the 'third assessor' is actually the cheif assessor! I read it on VCAA somewhere.