I wasn’t the first to publish the multiple choice answers but regret publishing it early. My purpose was for helping teachers. Wasn’t my intent to distress. I’m a marker yes, but not on examination board. In future I would definitely delay till after exams answers are released. which is what i did for the short answers
@@PhysicsHigh no, please upload them the day of the physics HSC exam. especially multiple choice. some people just want to know how they went, for the people who click on this they made a choice to find out. they could just wait until after to click on this.
I just found out about this Paul. I could not thank you enough. As a tutor it is always exciting to find different ways to explain this. I think in Q19 it would be easier to just go through the fact that the emf is the negative value of the variation of the magnetic flux over time. This variation is just BAcos(theta) where B, A and theta are the magnitude of the magnetic field, magnitude of the area and the angle between the normal of the area and the magnetic field. This angle is always 90 =implying cos(theta) =0 and thus the emf =0. Nonetheless, a big thank you!
Hey for question 6, shouldn't it be luminosity? The question states "approximately the same". Also, the axis of the diagram given is linear whilst the HR diagram axis for luminosity is logarithmic, therefore the entire graph is positioned within a tiny band of the entire HR diagram. Whilst the luminosity given for the cluster is visual rather than absolute, using the inverse distance law for distance (given that the cluster is 100 light years wide compared to its distance of 27000 light years away) we can see that even if we compare stars on opposite sides (one star being 26900 and the other being 27100), there is only a deviation of 2%, negligible within a logarithmic scale. Also, from wikipedia for globular cluster: "The formation of globular clusters remains a poorly understood phenomenon and it remains uncertain whether the stars in a globular cluster form in a single generation or are spawned across multiple generations over a period of several hundred million years." (Link: en.wikipedia.org/wiki/Globular_cluster# , under "formation section"), which indicates that the ages of the star vary widely.
no - the luminosity scale is logarithmic and a difference of 5 is a x100 change in brightness, so a range of 10 means x10 000 difference. Also, on the timescale of the life of the GC (~10 billion years +), the formation uncertainty is a couple of hundred million years makes the stellar sequence in the broader. (thanks to Geraint Lewis (Prof Cosmology at USyd) for this last bit.)
In a sense you can’t but that’s not how the question is designed. It ignores that issue and you are Simone comparing the 4 positions When Römer did this he did this over a period of years, thus taking this into account.
@@PhysicsHigh how do you think a year 12 student in an examination will go sorting out the intention of the examiner? The first thought most are likely to have is something to do with Kepler's Laws. The question is likely to disadvantage those who think through the implications of the supplied diagram. I am not very certain that the majority of students will have heard of Römer, especially as the relevant syllabus point is vague , I am supposing this is the reference ● conduct investigations of historical and contemporary methods used to determine the speed of light and its current relationship to the measurement of time and distance (ACSPH082) (I know you didn't write the question, - just asking your thoughts)
@@pkrauts I hear you, though you need not have studied Rømer to do the question. The question is written in a way that allows the student to determine the answer by problem solving. It is Q18, so not meant to be an easy question and is probably targeting higher ability students
at about 27:30 force on the electron is out of the page, not in? q2..." applied current" ? literacy of question setters needs to improve. q6 not appropriate for this syllabus...B C and D can be omitted, but the current syllabus does not discuss age in star clusters. Seems like a question from the old sly syllabus has sneaked its way in here. That's what the exam setters should be checking Otherwise thanks. I assume since you are senior HSC marker then this has been officially sanctioned by NESA?
I have removed your additional comment since it was incorrect and ill informed (though I did make the video unlisted and thus only visible to teachers, based on one aspect of your concern.) If you wish to discuss this further do so privately
For Q19 wouldn't the EMF at 3oClock make the electrons just move to the side of the object that is facing out of the page? so the side of the object closest to the reader is negatively charged? And when it moves to 9:00 the electrons will move into the page, and as it continually rotates the electrons will oscillate.
We notice that, for q18, you are assuming (and we think NESA is, too) that the observer did not correct for the time required for light to reach Earth (but perhaps did correct for parallax?). It does beg the question of what constitutes measurement and observation. My uni text on electrodynamics states, "...obviously, you must correct for the time the signal takes to reach you. When I speak of an 'observer', I mean someone having the sense to make this correction, and an 'observation' is what an observer records after doing so. What you see, therefore, is not the same as what you observe." Do we measure what we see or do we measure what we observe (post-correction)?
the Question models Rømer's work so it models what he observed and what he saw. He noted that the second measurement was a little later (for position Q) thus he (correctly) believed that the light had to travel a little further and thus was not an instantaneous thing. So this 'correction' you speak of is what Rømer used to determine the speed of light (this 'correction' he worked out to be 22 mins for the diameter of the earth .) Is this what you are after?
@@PhysicsHigh Thank you for your reply. However, no, this isn't what I am after. I would like NESA to test for physics ability - purely - in their Physics papers. This requires that ambiguities in question wording be avoided (and they have a history, sadly, of failing in this respect). Had the question stated that "an observer, several hundred years ago, had..." then we could work through the question in the context of Rømer. Recent papers have required a lot more integration of knowledge from across the syllabus, including the identification of parallax error influencing measurements (as seen in a projectile motion question). As the word "observation" clearly has subtly, but fundamentally, different meanings to different people, it seems, any possibility of a student heading down a different track to NESA's identified correct path should be eliminated with the simple use of explicit, unambiguous language. A little more care is all I ask for.
@@akaBaye don't have a record of the exact mark, but I beat the other people in the class by a landslide for the class marks. They don't give you an overall mark and one for the exam at the end, they just give you overall I believe.
I wish i never saw this
oath I got 4 multi's wrong
same
same
I wasn’t the first to publish the multiple choice answers but regret publishing it early. My purpose was for helping teachers. Wasn’t my intent to distress. I’m a marker yes, but not on examination board. In future I would definitely delay till after exams answers are released. which is what i did for the short answers
@@PhysicsHigh no, please upload them the day of the physics HSC exam. especially multiple choice. some people just want to know how they went, for the people who click on this they made a choice to find out. they could just wait until after to click on this.
Thank you for doing all this work Paul It is an immense help
Glad it has. Thanks
I just found out about this Paul. I could not thank you enough. As a tutor it is always exciting to find different ways to explain this.
I think in Q19 it would be easier to just go through the fact that the emf is the negative value of the variation of the magnetic flux over time.
This variation is just BAcos(theta) where B, A and theta are the magnitude of the magnetic field, magnitude of the area and the angle between the normal of the area and the magnetic field. This angle is always 90 =implying cos(theta) =0 and thus the emf =0.
Nonetheless, a big thank you!
Hey for question 6, shouldn't it be luminosity? The question states "approximately the same". Also, the axis of the diagram given is linear whilst the HR diagram axis for luminosity is logarithmic, therefore the entire graph is positioned within a tiny band of the entire HR diagram. Whilst the luminosity given for the cluster is visual rather than absolute, using the inverse distance law for distance (given that the cluster is 100 light years wide compared to its distance of 27000 light years away) we can see that even if we compare stars on opposite sides (one star being 26900 and the other being 27100), there is only a deviation of 2%, negligible within a logarithmic scale. Also, from wikipedia for globular cluster: "The formation of globular clusters remains a poorly understood phenomenon and it remains uncertain whether the stars in a globular cluster form in a single generation or are spawned across multiple generations over a period of several hundred million years." (Link: en.wikipedia.org/wiki/Globular_cluster# , under "formation section"), which indicates that the ages of the star vary widely.
no - the luminosity scale is logarithmic and a difference of 5 is a x100 change in brightness, so a range of 10 means x10 000 difference. Also, on the timescale of the life of the GC (~10 billion years +), the formation uncertainty is a couple of hundred million years makes the stellar sequence in the broader. (thanks to Geraint Lewis (Prof Cosmology at USyd) for this last bit.)
Hi Paul and thanks for your work. In Q18, why can we ignore the relative positions of earth and jupiter in their respective orbits?
In a sense you can’t but that’s not how the question is designed. It ignores that issue and you are Simone comparing the 4 positions
When Römer did this he did this over a period of years, thus taking this into account.
@@PhysicsHigh how do you think a year 12 student in an examination will go sorting out the intention of the examiner? The first thought most are likely to have is something to do with Kepler's Laws. The question is likely to disadvantage those who think through the implications of the supplied diagram. I am not very certain that the majority of students will have heard of Römer, especially as the relevant syllabus point is vague , I am supposing this is the reference ● conduct investigations of historical and contemporary methods used to determine the speed of light and its current relationship to the measurement of time and distance (ACSPH082) (I know you didn't write the question, - just asking your thoughts)
@@pkrauts I hear you, though you need not have studied Rømer to do the question. The question is written in a way that allows the student to determine the answer by problem solving. It is Q18, so not meant to be an easy question and is probably targeting higher ability students
at about 27:30 force on the electron is out of the page, not in?
q2..." applied current" ? literacy of question setters needs to improve.
q6 not appropriate for this syllabus...B C and D can be omitted, but the current syllabus does not discuss age in star clusters. Seems like a question from the old sly syllabus has sneaked its way in here. That's what the exam setters should be checking
Otherwise thanks.
I assume since you are senior HSC marker then this has been officially sanctioned by NESA?
He is just a teacher, I don’t think he is a marker. This definitely isn’t NESA-approved.
Correct. I may be a senior marker but that does NOT mean my videos are NESA endorsed.
I have removed your additional comment since it was incorrect and ill informed (though I did make the video unlisted and thus only visible to teachers, based on one aspect of your concern.) If you wish to discuss this further do so privately
Hey Paul, did you happen to write this year's paper by any chance? (Considering the Io question was in your speed of light video).
No. I teach year 12 so that prevents me from being an exam writer.
For Q19 wouldn't the EMF at 3oClock make the electrons just move to the side of the object that is facing out of the page? so the side of the object closest to the reader is negatively charged? And when it moves to 9:00 the electrons will move into the page, and as it continually rotates the electrons will oscillate.
It will, but there still isn't a flow of electric charge
We notice that, for q18, you are assuming (and we think NESA is, too) that the observer did not correct for the time required for light to reach Earth (but perhaps did correct for parallax?). It does beg the question of what constitutes measurement and observation. My uni text on electrodynamics states, "...obviously, you must correct for the time the signal takes to reach you. When I speak of an 'observer', I mean someone having the sense to make this correction, and an 'observation' is what an observer records after doing so. What you see, therefore, is not the same as what you observe."
Do we measure what we see or do we measure what we observe (post-correction)?
the Question models Rømer's work so it models what he observed and what he saw. He noted that the second measurement was a little later (for position Q) thus he (correctly) believed that the light had to travel a little further and thus was not an instantaneous thing. So this 'correction' you speak of is what Rømer used to determine the speed of light (this 'correction' he worked out to be 22 mins for the diameter of the earth .)
Is this what you are after?
@@PhysicsHigh Thank you for your reply. However, no, this isn't what I am after. I would like NESA to test for physics ability - purely - in their Physics papers. This requires that ambiguities in question wording be avoided (and they have a history, sadly, of failing in this respect). Had the question stated that "an observer, several hundred years ago, had..." then we could work through the question in the context of Rømer. Recent papers have required a lot more integration of knowledge from across the syllabus, including the identification of parallax error influencing measurements (as seen in a projectile motion question). As the word "observation" clearly has subtly, but fundamentally, different meanings to different people, it seems, any possibility of a student heading down a different track to NESA's identified correct path should be eliminated with the simple use of explicit, unambiguous language. A little more care is all I ask for.
Sorry, your question 16 is wrong, try again!
this question was 'hotly' debated on the physics forum. Would you like to argue your case
14 🤫🤫
hey what did you end up getting overall Exam mark? really curious thanks :)
17 I think. gg
hey bro what did you end up getting as your HSC exam mark? doing it this year really curious :) thank you
@@akaBaye 87 I think it was
@@zlatanibrahimovic8329 thanks g can you tell me what your Exam Mark Assessment Mark and overall HSC mark was?
maybe you got dragged down by your assessment or vice versa
@@akaBaye don't have a record of the exact mark, but I beat the other people in the class by a landslide for the class marks. They don't give you an overall mark and one for the exam at the end, they just give you overall I believe.
NMJ gonna sleep soon