ATAR Notes: Forum
Archived Discussion => 2010 => End-of-year exams => Exam Discussion => Victoria => Physics => Topic started by: bomb on November 10, 2010, 03:45:53 pm
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Heinemann Physics 12 states:
An increase in the amplitude of the sound wave corressponds to an increase in the volume or loudness of the sound, but the frequency and speed of the sound remain independent of change in volume and amplitude.
So, answer is A?
Also, for the Q where you had to state the LAW, could it be Lenz's law as well?
I mean, Lenz's law tells you the flux generated which in turn lets you use Faraday's Law.
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I really think that the question relating to the law isn't clear enough, and that they should accept either Lenz's or Faraday's.
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Yeah but at 3000Hz the microphone did not reproduce the sound identically, it had a +3dB change. Hence it was louder at the 3000freq, giving the increased amplitude.
Your definition stands correct but it doesn't account for how its the microphone's fault.
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yeah u need to take into account of the response curve of the microphone
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lol I can't remember the microphone, I'll have to check the exam :S
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I really think that the question relating to the law isn't clear enough, and that they should accept either Lenz's or Faraday's.
I said faraday's since I didn't invert my graph in the t-axis. My teacher said you could do either, when we had class tests/SAC. He knows his stuff and is 'friends' with the people associated with the writing of the exam, so I've invested a bit of trust in his knowledge there.
For sound, it was A... amp prop to loudness/intensity/volume (all the same thing in essence), frequency increased. Obviously A. If it isn't, I'mma shit bricks.
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pretty sure 10 is B
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im just posting so i can get an update when a confirmed answer comes through lol :)
if it mattera i said A and lenz
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pretty sure 10 is B
+1
yeah i think it should be B, it said they were the same intensity, but u had to refer the the graph, and the microphone was more sensitive to the higher frequency sound, so its amplitude had to be higher than the other sound.
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pretty sure 10 is B
+1
yeah i think it should be B, it said they were the same intensity, but u had to refer the the graph, and the microphone was more sensitive to the higher frequency sound, so its amplitude had to be higher than the other sound.
Mr.Chan hits the point home.
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c'mon A!
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B
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C ::)
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Damn, I needed those marks :(
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Question 10 the answer is definately A because, as the question stated "same intensity" - my thought process is, the amplitude determines the loudness of the sound (higher amplitude = higher energy = loud sound - wave propeties we learnt in light and matter). Therefore same intensity means same amplitude. Thus the only thing that changes is the period. Feel free to critisize but i am fairly certain its A ^____^
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Yeah sure that's the original sound though. However, the reading on the oscilloscope is read AFTER going through the microphone. Which does not reproduce both frequencies with the same intensity. :)
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C ::)
lol you cracked me up
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I really think that the question relating to the law isn't clear enough, and that they should accept either Lenz's or Faraday's.
BAHHHAA i wrote Faraday's law first.
Then read the question again and saw the "PHYSICAL" and that put me off.
I ended up writing Right hand palm rule. :(
DAMNNN.
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I really think that the question relating to the law isn't clear enough, and that they should accept either Lenz's or Faraday's.
BAHHHAA i wrote Faraday's law first.
Then read the question again and saw the "PHYSICAL" and that put me off.
I ended up writing Right hand palm rule. :(
DAMNNN.
if it makes you feel better i wrote conservation of energy, the physical law tripped me too )=
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Yeah wtf that three me off too!
But I couldn't strafe away from the ideal of Faraday's Law, so I just described it instead of stating it. Saying that a changing magnetic field would induce a voltage =[
Oh well, guess we'll both lose the one mark T__T
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Question 10 the answer is definately A because, as the question stated "same intensity" - my thought process is, the amplitude determines the loudness of the sound (higher amplitude = higher energy = loud sound - wave propeties we learnt in light and matter). Therefore same intensity means same amplitude. Thus the only thing that changes is the period. Feel free to critisize but i am fairly certain its A ^____^
I remember the question stating that both frequencies have the same intensity level "at the microphone" (i.e. where the sound enters the mic) therefore I am pretty sure that B is the correct answer.
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Maybe if we complain enough they'll make both answers right!
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I honestly feel that when they said the same sound intensities, that is a trap to lure you into choosing A
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I'm swayed. Answer's B.
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Yeah sure that's the original sound though. However, the reading on the oscilloscope is read AFTER going through the microphone. Which does not reproduce both frequencies with the same intensity. :)
I don't recall this question clearly, but did it say the microphone was connected to the oscilloscope? You can hook up signal generators to oscilloscopes, you know...
But if you're right then that makes sense. I don't recall observing there being ANY link between two questions in sound other than the dB one. Aww...
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I'm pretty sure they said "Refer to this diagram for Question 9-10"
If not, then your arguments are right and its A.
The only reason I chose B because that was a follow up question ><
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I don't remember what I chose but I chose the one with the higher amplitude and a shorter period.
Hope that's right.
As for the law, I bloody wrote Lenz's. FML.
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I don't remember what I chose but I chose the one with the higher amplitude and a shorter period.
Hope that's right.
As for the law, I bloody wrote Lenz's. FML.
I wouldn't be surprised if they accepted both. On the formula sheet they do cite Lenz's Law as V = -n(d[fi]/dt) don't they? So if you did invert the graph it'd make sense. I went with Faraday's because I didn't invert my graph, as per my teacher (former markerer person) it doesn't matter and he'd accepted mine as rightin SACs.
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I don't remember what I chose but I chose the one with the higher amplitude and a shorter period.
Hope that's right.
As for the law, I bloody wrote Lenz's. FML.
I wouldn't be surprised if they accepted both. On the formula sheet they do cite Lenz's Law as V = -n(d[fi]/dt) don't they? So if you did invert the graph it'd make sense. I went with Faraday's because I didn't invert my graph, as per my teacher (former markerer person) it doesn't matter and he'd accepted mine as rightin SACs.
pretty sure you have to invert the graph.
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Are you guys talking about early on in the exam in the first section for the 1 mark? It asked "who's law" thingy? Yeah for that I wrote Lenz's. Just trying to make sure we're talking about the same question.
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With regards to Question 10 in the sound section; it says on my Statement of Marks that came through today that they accepted both A and B.
In case anyone is still interested (I doubt it :P)
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Haha, yes! I'm glad about that.. I wan't wrong. ::)
I wonder how many marks I lost then.. Maybe I'll get SoM.
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I wonder why they accepted both.. hmm
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Because students were confused about whether the question was related to the previous information. I suppose there were enough complaints/comments from teachers about this issue for them to consider it.
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Because students were confused about whether the question was related to the previous information. I suppose there were enough complaints/comments from teachers about this issue for them to consider it.
kinda unfair but oh well doesn't matter now.