ATAR Notes: Forum
Archived Discussion => Mathematics and Science => 2012 => End-of-year exams => Exam Discussion => Victoria => Physics => Topic started by: #1procrastinator on November 14, 2012, 01:44:13 pm
-
Bloody disaster for me. I forgot to include a couple of formulas in my notes
and that resulted in me not being able to complete a couple of questions. Think I'd be lucky
to get 50%. That's what you get for trying to cram everything into 7 hours before the exam.
Ah well, can't do anything bout it now.
Third time's a charm, see you next year class of '13, hahahahahahahaha
-
I found it fairly easy, however it was a bit more time consuming than other years. Probably got at least 2 MC wrong and maybe some worded marks. Overall I was pretty happy.
-
How did you go with AC motor question?
-
That took a bit of thought, finding the current relied on unit 3 electricity. I just found the voltage drop over the power lines using the resistances, and then divided it by the resistance to find the current. I still found it took a while.
-
I promised myself I won't read this thread... It's going to make me worry more than I want to.
Before this thread flies, I found electricity pretty good, light not so good, Detailed, alright.
I'll stop here!
Hope everyone did well!!
-
For the question about two methods to reduce power loss...
First was obviously use a transformer.
But the second was confusing me. I was initially thinking to decrease the resistance by using thicker wires or a better conductor or electricity, but because I=V/R, if R decreases then I increases! And because PLoss=I^2R, any slight increase in I will be squared and actually increase the power loss by quite a bit.
So I eventually said to 'add more transmission wires in parallel', but that's effectively the same as decreasing R/increasing I, and at that point I gave up.
So which of the answers for the second method is correct (1: decrease R, or 2: add in parallel)? Are none correct, is one correct and the other isn't, or are both correct?
very confuzzled
-
fuck fuck fuck. I fucked up the whole transmission question, 5 marks definitely gone! I dont know what I was thinking, I went: I=V/R=900/18=50A but i know thats wrong fuck. Then I used that for the next 3 mark question. Please can anyone help me: If I used the wrong current of 50A in determining the Power loss in the next question, would I get ANY consequential marks? Please I need this answered Im dying! :(
-
Moderate exam.
There were many easy marks, but a few difficult marks. I doubt I'll be getting an A+.
My prediction for the cutoff is approximatly 89%.
The path difference question which required you to find the new wavelength will seperate students, and a lot will get caught up in finding the energy of one X-ray photon. Lastly that electron shell question was very difficult, I spoke about standing waves ect but doubt I'll be getting 3/3 for that one.
-
#### - I couldn't finish it!! :( :( :(
Physics was my only hope... Anyone else find it a tad too long?!
what do you think the A+ cut-off score will be?
#@$%!
-
fuck fuck fuck. I fucked up the whole transmission question, 5 marks definitely gone! I dont know what I was thinking, I went: I=V/R=900/18=50A but i know thats wrong fuck. Then I used that for the next 3 mark question. Please can anyone help me: If I used the wrong current of 50A in determining the Power loss in the next question, would I get ANY consequential marks? Please I need this answered Im dying! :(
You will lose one mark max, assuming you showed working for the other questions. Relax you will be fine.
-
i forgot to put the line at NE i just put it as east fuck my lifeeeeee
im the only one who got q1 wrong :(
-
I did that too. Sheeeeeeeeeeeeeeeeeeeeeeeeeeeeeit. What was the next one? I just guessed and put the unchanged one
-
So which of the answers for the second method is correct (1: decrease R, or 2: add in parallel)? Are none correct, is one correct and the other isn't, or are both correct?
very confuzzled
For the 2nd method decrease R is correct
-
i forgot to put the line at NE i just put it as east fuck my lifeeeeee
im the only one who got q1 wrong :(
I'm not actually sure if it's NE, someone said it was SE, because the arrow was pointing at magnetic north. We'll need a copy of the exam to see.
Pretty neat exam, nothing out of the ordinary. Might have lost a mark on that first question, and probably dropped some in those bloody explain questions.
-
fuck fuck fuck. I fucked up the whole transmission question, 5 marks definitely gone! I dont know what I was thinking, I went: I=V/R=900/18=50A but i know thats wrong fuck. Then I used that for the next 3 mark question. Please can anyone help me: If I used the wrong current of 50A in determining the Power loss in the next question, would I get ANY consequential marks? Please I need this answered Im dying! :(
You will lose one mark max, assuming you showed working for the other questions. Relax you will be fine.
Thank you for your kind words, however the way I alculated the current was completely illogical since I just assumed that the motor would get 900V in th first place. I then went on to calculate the power loss which left the motor with less than the required power to use 9000V. Do you get what Im saying? But if I applied the rules correctly:Ploss=I^2R how many method marks am I looking at, 1 out o the total 3?
-
I stuffed up. I left six marks out because I was running out of time. The other questions that I managed were badly done.
Itute has posted up their suggested solutions: http://www.itute.com/board/viewtopic.php?f=6&t=2500
-
I'm assuming the answer to 1 was SE as the arrow pointing up was magnetic north, the field will be going down therefore adding the vectors gives south east
-
I am pretty happy with the Electric Power and Synchrotron sections. However despite doing amazingly for time for most of the exam. I managed to run out of time on light. I think I guessed/didn't answer 10 marks worth. :-[ I should hopefully make up for it with what I thought were some pretty decent responses to all the explain questions and what looks like some a good number of answers that I can remember matching itute. Will probably end up with a B like my mid year, however a B+ or A probably isn't completely out of the question at this stage. :)
-
I stuffed up. I left six marks out because I was running out of time. The other questions that I managed were badly done.
Itute has posted up their suggested solutions: http://www.itute.com/board/viewtopic.php?f=6&t=2500
Whattt I thought 1 b) was C.
-
I'm assuming the answer to 1 was SE as the arrow pointing up was magnetic north, the field will be going down therefore adding the vectors gives south east
Why would it be backwards? Magnetic North is "Magnetic North" the North Magnetic pole of the earth located in Antarctica where the south geographic pole is?
-
I stuffed up. I left six marks out because I was running out of time. The other questions that I managed were badly done.
Itute has posted up their suggested solutions: http://www.itute.com/board/viewtopic.php?f=6&t=2500
Whattt I thought 1 b) was C.
It should have been the one with the North pole of the magnet was pointing left, whatever that answer was. Unless I'm wrong. XD
Edit: Oh, wait sorry. I think I see where the confusion is. I'm pretty sure by NE itute mean 'up right', or 45 degrees from the x axis roughly the direction the top of this forward slash points / or however you want to describe it.
-
I think the most important thing is, the exam is over.
-
I stuffed up. I left six marks out because I was running out of time. The other questions that I managed were badly done.
Itute has posted up their suggested solutions: http://www.itute.com/board/viewtopic.php?f=6&t=2500
Whattt I thought 1 b) was C.
It should have been the one with the North pole of the magnet was pointing left, whatever that answer was. Unless I'm wrong. XD
Yep that was C.
I got massively confused about the entire question because if you incoporate the earth's magnetic field NONE of the options were correct, I think that confused some people. Only when I reread it did I realise you were meant to ignore the earth's field.
-
Anyone else get different results for Light and Matter 1 c) and d)
Or am I screwed :(
-
I personally didn't find it too bad. The questions seemed trickier than some of the past vcaa exams and required a good understanding of how concepts relate to each other. I probably got that path difference question wrong, and the sound mc questions felt harder than previous years. Hopefully I did alright.
-
Anyone else get different results for Light and Matter 1 c) and d)
Or am I screwed :(
I got 0.825 for at least one of my answers somewhere. That doesn't mean you're screwed though.
-
i have a feeling there was a big trick question in there.
the question which showed the 2 magnets, and had like, A and B. it asked which direction the coil moved once the motor was swtiched on.
well anyway, the magnet had N and S on the top, and were shaded.
so..
the magnetic field wasnt going from North to south horizontally
it was going in an arch.
-
Can someone upload the paper pls....
-
Anyone else get different results for Light and Matter 1 c) and d)
Or am I screwed :(
I got 0.825 for at least one of my answers somewhere. That doesn't mean you're screwed though.
Hmm. If I got c) wrong, and used my answer from c for d), would I get the mark from consequential working or not? :\
-
I'm assuming the answer to 1 was SE as the arrow pointing up was magnetic north, the field will be going down therefore adding the vectors gives south east
Why would it be backwards? Magnetic North is "Magnetic North" the North Magnetic pole of the earth located in Antarctica where the south geographic pole is?
There's no indication of where the geographic poles just the magnetic poles which are going from up to down on the page
-
Here's hoping for a low cut-off, really need a C+
-
thought the first and second question were tricky. 1st question got south east, and second question I said the magnet remained the same as the question told us to ignore earth's magnetic field and the megnetic field at point Q was very weak hence the magnet satyed the same. what did everyone else get?
-
The exam wasn't too bad. Sound was very, very straight forward! In fact.. all of the sound questions were pretty much identical to the VCAA papers. The exam in general was pretty long though. Just finished with like 3 seconds to go haha.
-
Science damn it, I didn't have time to go over the sound part of the past exams
-
Science damn it, I didn't have time to go over the sound part of the past exams
I "did a rohit" - I learnt what Lenz's law and what a standing wave was ON the day of the exam..
In fact, if my friends didn't tell me that changing slip (SPLIT ? IDK LOL WHO GIVES A FK) rings for a commutator results in pulse DC, I would have lost like 2 marks LOL.
DATCRAM
GETTING READY FOR UNI ALREADY
-
fuck fuck fuck. I fucked up the whole transmission question, 5 marks definitely gone! I dont know what I was thinking, I went: I=V/R=900/18=50A but i know thats wrong fuck. Then I used that for the next 3 mark question. Please can anyone help me: If I used the wrong current of 50A in determining the Power loss in the next question, would I get ANY consequential marks? Please I need this answered Im dying! :(
You will lose one mark max, assuming you showed working for the other questions. Relax you will be fine.
Thank you for your kind words, however the way I alculated the current was completely illogical since I just assumed that the motor would get 900V in th first place. I then went on to calculate the power loss which left the motor with less than the required power to use 9000V. Do you get what Im saying? But if I applied the rules correctly:Ploss=I^2R how many method marks am I looking at, 1 out o the total 3?
Anyone have any idea? thanks
-
For the question about two methods to reduce power loss...
First was obviously use a transformer.
But the second was confusing me. I was initially thinking to decrease the resistance by using thicker wires or a better conductor or electricity, but because I=V/R, if R decreases then I increases! And because PLoss=I^2R, any slight increase in I will be squared and actually increase the power loss by quite a bit.
So I eventually said to 'add more transmission wires in parallel', but that's effectively the same as decreasing R/increasing I, and at that point I gave up.
So which of the answers for the second method is correct (1: decrease R, or 2: add in parallel)? Are none correct, is one correct and the other isn't, or are both correct?
very confuzzled
hah...you should have went with thicker wires...cause the resistance is inversely proportional to cross-sectional area...but its ok...i thought that exam was a bit on the hard side...:D
-
i have a feeling there was a big trick question in there.
the question which showed the 2 magnets, and had like, A and B. it asked which direction the coil moved once the motor was swtiched on.
well anyway, the magnet had N and S on the top, and were shaded.
so..
the magnetic field wasnt going from North to south horizontally
it was going in an arch.
I thought the same, but dismissed the idea on the basis that it was a VCAA exam, not Itute lol. It could still be right, but it seems too damn ambiguous. The top half of the DC power supply was shaded too, so I really can't tell.
-
Science damn it, I didn't have time to go over the sound part of the past exams
I "did a rohit" - I learnt what Lenz's law and what a standing wave was ON the day of the exam..
<3
-
Just to clarify:
Magnetic north does not refer to the "north pole" if you were to imagine earth as a bar magnet.
Magnetic north is the direction in which a compass needle says north is. This is different to "true north" which is towards the North pole (The geographical one in the Arctic). Going with the earth-is-a-bar-magnet idea, magnetic north can be equated to that magnet's south pole.
-
Can someone tell me what Study Score a High C+ on exam 1 (~60/90) then A/A+ on Exam 2 is (~84/90)
-
Just to clarify:
Magnetic north does not refer to the "north pole" if you were to imagine earth as a bar magnet.
Magnetic north is the direction in which a compass needle says north is. This is different to "true north" which is towards the North pole (The geographical one in the Arctic). Going with the earth-is-a-bar-magnet idea, magnetic north can be equated to that magnet's south pole.
Looking that up, holy crap, you're right. While I'm happy that I got that mark, this is some of the least intuitive crap I've ever seen...
-
Shouldn't the first answer be North West. The field of the solenoid pointed west while the field of the Earth pointed north. Addition of vectors gives you North West. Or maybe I made a mistake in the exam room. All in all, good paper, some hard questions (I love you VCAA, made up for the easy methods one).
-
Shouldn't the first answer be North West. The field of the solenoid pointed west while the field of the Earth pointed north. Addition of vectors gives you North West. Or maybe I made a mistake in the exam room. All in all, good paper, some hard questions (I love you VCAA, made up for the easy methods one).
Solenoid pointed east unfortunately!
-
Shit :/, thought I nailed the crap out of that one. Oh well, still eludes me how I got part two correct though. 100% said C
-
Electric power and Synchrotron were alright, few complicated questions in Electric power but that was about it. But when I looked at Light and matter.....
(http://thimg.todayhumor.co.kr/upfile/201211/1352813872198.jpg)
Not enough time to finish it :(. Probably only got like 6/20 from it.... Hopefully I get a C+...
-
Just to clarify:
Magnetic north does not refer to the "north pole" if you were to imagine earth as a bar magnet.
Magnetic north is the direction in which a compass needle says north is. This is different to "true north" which is towards the North pole (The geographical one in the Arctic). Going with the earth-is-a-bar-magnet idea, magnetic north can be equated to that magnet's south pole.
Looking that up, holy crap, you're right. While I'm happy that I got that mark, this is some of the least intuitive crap I've ever seen...
Unfortunately the definition doesn't have origins in Physics, where, given the prevalence of the bar magnet analogy, it is unintuitive. "Magnetic North" is primarily a navigational term and it is one of three North points you might find on any topographical map. It refers to north as given by a compass, as opposed to north given by the direction to the north pole or north given by the direction of Eastings (the vertical lines on a map).
-
Thought was standard VCAA physics in every way.
-
Wasn't too bad of an exam imo.
For the magnetic flux MC question. The second one asking for the EMF, all answers were wrong. I said D because it was not too bad of an answer, but it was essentially not correct.
-
In the same way we define up as positive and down as negative when dealing with forces etc, voltage can be defined as positive or negative depending on the point of reference. So although yes the directions on the emf-t graph multiple choice question are upside down, we have been trained to only deal with conventional current, if we simply switch polarity, what we take reference from has changed, and the result would be D.
Another point there is, no value are on the y-axis. It's not absurd to have negative values above the x-axis and positive values below.
Just some things to consider. Answer's D nonetheless.
-
Wasn't too bad of an exam imo.
For the magnetic flux MC question. The second one asking for the EMF, all answers were wrong. I said D because it was not too bad of an answer, but it was essentially not correct.
Yeah, that question was fucked haha. D was the least incorrect so I went with that.
-
in the exam I wrote down that all answers are incorrect and draw the correct one.
Still wrote down D of course
-
Wow, most of answers to my exam matched itute :). Surely i'll get a better grade for this exam than the C i got for unit 3
-
Only 2 MC questions wrong, is that A+ territory? Predicted study score for a middle B+ exam 1 and only 2 MCQs wrong in exam 2?
-
Wasn't too bad of an exam imo.
For the magnetic flux MC question. The second one asking for the EMF, all answers were wrong. I said D because it was not too bad of an answer, but it was essentially not correct.
Can't remember this one, don't htink i put D, was this the one where he moves that coil out of the field?
(what were the 4 options?)
-
Wasn't too bad of an exam imo.
For the magnetic flux MC question. The second one asking for the EMF, all answers were wrong. I said D because it was not too bad of an answer, but it was essentially not correct.
Can't remember this one, don't htink i put D, was this the one where he moves that coil out of the field?
(what were the 4 options?)
The question for the EMF not the flux.
A was a trapezium (correct for flux)
B was a triangle
C was a different triangle
D were 2 boxes one positive and one negative (correct one for the aforementioned emf question)
-
Wasn't too bad of an exam imo.
For the magnetic flux MC question. The second one asking for the EMF, all answers were wrong. I said D because it was not too bad of an answer, but it was essentially not correct.
It had no scale on the EMF axis, so there was no way of knowing which was positive and which was negative. So D was the correct answer, not just the least incorrect
-
Usually those EMF graph questions are worded "best describe". That doesn't mean the answer has to be correct, but just needs to be the best out of the four to represent the EMF graph.
-
Just checking, which was 'D' for the emf question. Was it the graph that had a negative value followed by 0 then a positive value?
-
Just checking, which was 'D' for the emf question. Was it the graph that had a negative value followed by 0 then a positive value?
`twas indeed