ATAR Notes: Forum
VCE Stuff => VCE Science => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Physics => Topic started by: BasicAcid on September 23, 2013, 05:57:01 pm
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I just printed mine today! But I left blank space for annotations, diagrams and some sample answers
It sounds like you managed to fit in more content than me haha
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It going to be annoying to refer to such a big sheet of paper in the exam. So far I've put most of U4 on the paper (digitally still). I got U3 stuff done from when I did the SACs. People should start posting their A3 cheat sheets in the notes :)
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What was your detailed study?
Definitely not necessary for the cheat sheet to be that big. But I don't necessarily think that it'll mean the A+ cutoff is that high. I would've thought that almost all of the A+ students would basically know all their stuff, and won't really forget much, and that the differentiation between students would come from their:
1. careless errors
2. ability to solve the couple of harder questions they put in the exam. A3 may be big, but it's not big enough to put every hard question VCAA might ask on it.
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What was your detailed study?
Definitely not necessary for the cheat sheet to be that big. But I don't necessarily think that it'll mean the A+ cutoff is that high. I would've thought that almost all of the A+ students would basically know all their stuff, and won't really forget much, and that the differentiation between students would come from their:
1. careless errors
2. ability to solve the couple of harder questions they put in the exam. A3 may be big, but it's not big enough to put every hard question VCAA might ask on it.
I disagree with 2. An A3 sheet of paper is crazy. If it's double-sided too...dear me...
There are only so many hard questions in VCE, and if you shrink the font size, you could fit so much it wouldn't be funny.
I think we're allowed 2 A4 instead as well.
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You're actually going to contend that you could fit every conceivable hard question that VCAA might ask would fit on a sheet of double-sided A3 paper.
I don't mean 'hard questions VCAA has asked in the past'. I mean 'every hard question which could conceivably be asked of VCE physics students'. And by hard, I don't mean no one at VCE level can do them, I mean that most people would find it difficult.
If you look at the possibilities available, you can't fit them on an A3 sheet of paper. Even if it's double sided.
I may be underestimating people's abilities, but if you asked people why an ideal transformer's primary coil has no current in it if no current can flow through the secondary coil, pretty sure not many VCE physics students would know, even if I think it would fall within the realms of the course. Even in motion, if you asked people: in a helium balloon released from rest floating upwards, it gains both kinetic energy and gravitational potential energy, where does that energy come from? I'm pretty sure that would qualify as a 'hard' question.
I think that the number of hard questions VCAA could ask is too high to fit on a sheet of A3 paper.
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You're actually going to contend that you could fit every conceivable hard question that VCAA might ask would fit on a sheet of double-sided A3 paper.
I don't mean 'hard questions VCAA has asked in the past'. I mean 'every hard question which could conceivably be asked of VCE physics students'. And by hard, I don't mean no one at VCE level can do them, I mean that most people would find it difficult.
If you look at the possibilities available, you can't fit them on an A3 sheet of paper. Even if it's double sided.
I may be underestimating people's abilities, but if you asked people why an ideal transformer's primary coil has no current in it if no current can flow through the secondary coil, pretty sure not many VCE physics students would know, even if I think it would fall within the realms of the course. Even in motion, if you asked people: in a helium balloon released from rest floating upwards, it gains both kinetic energy and gravitational potential energy, where does that energy come from? I'm pretty sure that would qualify as a 'hard' question.
I think that the number of hard questions VCAA could ask is too high to fit on a sheet of A3 paper.
Let's see...
I'm sure heaps of people know how transformers work through induction. That IS on the course. No current => constant magnetic field => nothing induced.
As for your helium balloon question, that's not really VCE physics as buoyant forces aren't really part of the course.
There are only so many concepts in VCE physics; writing out each one in detail is not a problem for a double-sided sheet of A3. Write them out in detail and that's all that is needed. Hard questions would have to fall under the category of concepts in VCE physics.
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Let's see...
I'm sure heaps of people know how transformers work through induction. That IS on the course. No current => constant magnetic field => nothing induced.
As for your helium balloon question, that's not really VCE physics as buoyant forces aren't really part of the course.
There are only so many concepts in VCE physics; writing out each one in detail is not a problem for a double-sided sheet of A3. Write them out in detail and that's all that is needed. Hard questions would have to fall under the category of concepts in VCE physics.
I don't think that's the right way to go about the first question. He's saying that an AC voltage is applied to the primary, but the secondary coil is disconnected or broken. In this case, no current will flow in the primary, and your suggestion doesn't seem to explain why. I think it's because of the Back EMF from that basically negates the current that induces it. You would have to explain it by Lenz's Law I think.
As for the second one, you could still explain that by the fact that it's not an isolated system; while buoyancy isn't part of the course, the balloon is displacing air which is losing gravitational potential as it falls below the balloon.
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I don't think that's the right way to go about the first question. He's saying that an AC voltage is applied to the primary, but the secondary coil is disconnected or broken. In this case, no current will flow in the primary, and your suggestion doesn't seem to explain why. I think it's because of the Back EMF from that basically negates the current that induces it. You would have to explain it by Lenz's Law I think.
As for the second one, you could still explain that by the fact that it's not an isolated system; while buoyancy isn't part of the course, the balloon is displacing air which is losing gravitational potential as it falls below the balloon.
Yeah ok, I misinterpreted the question.
If no current can flow in the secondary, then yeah any change in magnetic flux through the transformer would be opposed by Lenz's law.
I think with your explanation, you'd still have to explain why air is displaced; a balloon filled with metal doesn't displace air in that way, for instance.
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I'm not saying you can't do them, nliu1995.
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So this year we are allowed to bring in 2 double sides a4 sheets of paper?
It's the same size as A3 I personally feel splitting unit 3 to one sheet and unit 4 to the other is more logical
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So this year we are allowed to bring in 2 double sides a4 sheets of paper?
It's the same size as A3 I personally feel splitting unit 3 to one sheet and unit 4 to the other is more logical
You've made the assumption that units 3 and 4 both require the same amount of notes. For starters, the unit with the detailed study will have more areas of study.
Also, different areas of study will require varying amounts of notes. You can't expect all topics to require the same amount of notes.
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You've made the assumption that units 3 and 4 both require the same amount of notes. For starters, the unit with the detailed study will have more areas of study.
Also, different areas of study will require varying amounts of notes. You can't expect all topics to require the same amount of notes.
Do you have any notes at all? O_O
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Guys, you're going about this the wrong way. You could easily get an A2 sheet from this A3 page.
(http://i40.tinypic.com/123mplh.png)
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Hahahaha I saw that in the engineering memes page on facey!
You wouldn't happen to be a contributor to the page would you Hancock...?
Guessing he got it from reddit, before it ended up on that page :P (I'd find the link, but ceebs)
EDIT: There we go: http://www.reddit.com/r/funny/comments/1n6t00/my_professor_said_i_could_only_use_one_notecard/
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Guessing he got it from reddit, before it ended up on that page :P (I'd find the link, but ceebs)
EDIT: There we go: http://www.reddit.com/r/funny/comments/1n6t00/my_professor_said_i_could_only_use_one_notecard/
Doing the Repost God's work.
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Hey Social Rhubarb,
I still don't quite understand how the Back EMF concept works? I am just thinking - if the secondary coil circuit has no load, the primary current will just keep circulating wouldn't it? What is this back EMF and where on earth does it come from??
Doesn't the transformer then just work like a normal solenoid with an iron core? (lel, i am part of that majority that don't know my shit..)
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Hey Social Rhubarb,
I still don't quite understand how the Back EMF concept works? I am just thinking - if the secondary coil circuit has no load, the primary current will just keep circulating wouldn't it? What is this back EMF and where on earth does it come from??
Doesn't the transformer then just work like a normal solenoid with an iron core? (lel, i am part of that majority that don't know my shit..)
I'm not SocialRhubarb :P
If the secondary coil circuit has no load, the primary coil can still induce an emf and current to oppose the changing magnetic flux through it. If your primary coil had a constant current, then yes it would keep going, but your transformer wouldn't work. Note that as your secondary coil circuit is empty, it's effectively not there as a current can't be induced.
If your secondary coil does have a load, a current is induced in the secondary coil in the same direction as the back emf in the primary coil. This induced current itself also generates a changing magnetic field which induces another current in the primary to oppose the induced current. This second induced current in the primary is of opposite sign to the induced current in the secondary, which is of the opposite sign to the original current. Therefore the second induced current in the primary coil SUPPORTS the original current and emf. Thus having a load in the secondary coil makes a world of difference.
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So this year we are allowed to bring in 2 double sides a4 sheets of paper?
It's the same size as A3 I personally feel splitting unit 3 to one sheet and unit 4 to the other is more logical
But they must be bound together with tape so you might as well bring in an A3 sheet.
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Yep, basically what nliu1995 said.
It's interesting though that solenoids by themselves actually experience this too, and solenoids without a load do not, as some would predict, have huge currents passing through them when a voltage is applied, but instead reach a modest current, with the scale of the current depending on the nature of your solenoid, and how close it is to ideal.
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Lol, ok so to reiterate. The AC current in the primary coil creates a changing magnetic field which is basically counterproductive for itself as the very same primary coil will try to offset this changing magnetic flux with a "Back EMF" - so no current.
However, with a load in the secondary coil, the AC current can flow in the secondary coil, which basically negates that Back EMF, so its all good and the current keeps circulating?
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Not really negate...but you have the basic idea.
I'd prefer "an AC current" rather than "the AC current" as we're not speaking about only one possible current.
But yeah, it's like we've induced two current from the initial AC currents and the second induced current partially offsets the back EMF.
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wtf, double-sided A3?!
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Righto, although I think it should be just an AC (cus AC stands for alternating current) - AC current would mean alternating current current, a bit redundant :P
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Is a laminated cheat sheet allowed?
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Is a laminated cheat sheet allowed?
Even though its not stated whether or not you are allowed, I'd say probably not. I wouldn't take the risk.
May be ask your VCE Coordinator or Physics teacher? ???