HSC Physics Question Thread

[winstondarmawan]

Ahaha hey! I think towards 4 at the bottom, towards 1 at the top. If you consider the bottom, we have a N pole moving towards the bottom - So we want to push the N away (Lenz's Law). So, by the right hand grip rule, we want to induce a counter clockwise current - That generates a north pole equivalent field directed towards the magnet to oppose its motion. Then the top is just the opposite - We want a north pole directed downwards to try and bring the S pole back up. Therefore, clockwise current

This was just a quick run through - But does it make sense? (who won the argument? Ahaha)

Yes thank you! I did

[jamonwindeyer]

Yes thank you! I did

Nicely done

[Jyrgal]

All of this comes down to Lorentz transformations, which are NOT in the syllabus for some reason. For instance, I think that first question is totally easy, just as straight forward as the usual relativity question, IF YOU WERE GIVEN THE FORMULA! However, you're not, so for now I would just focus on what is actually assessable.

Re your second question; no idea, Relativity doesn't really like acceleration, the maths gets too tough.

Oh haha, i think the questions r from a sheet my friend got from his teacher... maybe not hsc related, no wonder it had me confused the whole day

[scienceislife]

Do you find that general physics text books or reliable websites are better for research assessment tasks?

[jakesilove]

Do you find that general physics text books or reliable websites are better for research assessment tasks?

Use both! Markers will look kindly on you if you use a variety of sources, including online and physical sources

[bsdfjnlkasn]

Hey just chiming in with the research assessment question, where can I find good journal articles for semiconductors and transistors (3rd dotpoint set in I2I) as I don't know where to look and what to search. Any advice or links would be super appreciated - our bibliography has to assess the accuracy, validity and reliability of the sources and ideally they would all fulfil these requirements

[jamonwindeyer]

Hey just chiming in with the research assessment question, where can I find good journal articles for semiconductors and transistors (3rd dotpoint set in I2I) as I don't know where to look and what to search. Any advice or links would be super appreciated - our bibliography has to assess the accuracy, validity and reliability of the sources and ideally they would all fulfil these requirements

Hey! Are you looking for sources that demonstrate how they are used? Any electrical engineering textbooks for uni would suit you - Does it have to be a journal article or?

[bsdfjnlkasn]

Hey! Are you looking for sources that demonstrate how they are used? Any electrical engineering textbooks for uni would suit you - Does it have to be a journal article or?

Mostly just explanations/general info about the dot points in that section of I2I
We are required to have a variety of source forms, so a journal article would definitely help (considering I've only used textbooks so far) - if you've got any additional suggestions I'd love to hear them!

[arunasva]

What are the effects of Gravitational fields and changing electric fields on the Meissner effect ?

I have to explain this in a video while conducting the Meissner Effect prac. I am thinking for gravitational field I have to say F=qE is > than -(F=mg)  ?

[jamonwindeyer]

Mostly just explanations/general info about the dot points in that section of I2I
We are required to have a variety of source forms, so a journal article would definitely help (considering I've only used textbooks so far) - if you've got any additional suggestions I'd love to hear them!

Hmm - Unfortunately nothing springs to mind, a lot of the journal articles you'd find on that topic would be quite academically rigorous, written as a Thesis perhaps. Hopefully someone else might know one!

(Have you checked any article databases? Normally your library can give you access to some (the names all elude me now but they were super useful back when I did my HSC)

[katnisschung]

Hi so i have an assessment coming up which is a research task on superconductivity
it covers 7 dotpoints (4.4,4.5, 4.6, 4.7 and from the investigations column 4.1.3, 4.1.4, 4.1.5)

I haven't been transcribing any notes this term becos i've been quite busy with work and assessments
will prior knowledge on the previous focus areas of ideas to implementation be necessary to understand these
dotpoints (such as the bcs theory) the test will only be on these dotpoints however I have limited time so looking for the
most efficient manner to do this task (either transcribe everything i've done till this point or just do the research for these dotpoints and transcribe after the exam)

thanks

[julies]

I found that prior knowledge of i2i dot points was not that helpful, except maybe the idea of quantised energy for phonons. The most relevant things were probably from motors and generators, i.e. resistance, Lenz's and Faraday's Law (for the Meissner effect and maglev trains)
I would just do a lot of questions on research dot points!

[pikachu975]

I found that prior knowledge of i2i dot points was not that helpful, except maybe the idea of quantised energy for phonons. The most relevant things were probably from motors and generators, i.e. resistance, Lenz's and Faraday's Law (for the Meissner effect and maglev trains)
I would just do a lot of questions on research dot points!

Lenz's law doesn't govern how the Meissner effect works despite people saying it does, it works by quantum mechanics. You don't have to say how it works you just need to say what it is.

[jamonwindeyer]

I found that prior knowledge of i2i dot points was not that helpful, except maybe the idea of quantised energy for phonons. The most relevant things were probably from motors and generators, i.e. resistance, Lenz's and Faraday's Law (for the Meissner effect and maglev trains)
I would just do a lot of questions on research dot points!

Lenz's law doesn't govern how the Meissner effect works despite people saying it does, it works by quantum mechanics. You don't have to say how it works you just need to say what it is.

This is very true - The principle is similar but distinct. I think this paragraph excerpt from the explanation on Wikipedia explains it well (as much as using Wikipedia is discouraged, the explanations it gives for scientific principles are usually quite a nice way to introduce a concept )

Any perfect conductor will prevent any change to magnetic flux passing through its surface due to ordinary electromagnetic induction at zero resistance. The Meissner effect is distinct from this: when an ordinary conductor is cooled so that it makes the transition to a superconducting state in the presence of a constant applied magnetic field, the magnetic flux is expelled during the transition. This effect cannot be explained by infinite conductivity alone. Its explanation is more complex and was first given in the London equations by the brothers Fritz and Heinz London. It should thus be noted that the placement and subsequent levitation of a magnet above an already superconducting material does not demonstrate the Meissner effect, while an initially stationary magnet later being repelled by a superconductor as it is cooled through its critical temperature does.

Placing a magnet above an already superconductive material does not demonstrate the Meissner Effect. A magnet beginning to hover as it becomes superconductive does demonstrate the effect. This is very easy to confuse (and not important at this level of study either, saying that a magnet placed above a superconductor hovers in place due to the Meissner Effect has always done fine from what I've seen, just interesting!)

The big point for you guys is to understand that the Meissner effect is separate and distinct from Lenz's Law/Induction. As pikachu said, you don't need to explain Meissner, just say that it (exclusion of magnetic flux from a superconductor below critical temperature) occurs

Another good explanation here covering some of those more finicky (and not so relevant) points

To Katniss, just research the relevant dot points and make some palm cards to study from - Worry about the rest later

[bsdfjnlkasn]

Hey there,

We've just gone through p and n-type semiconductors in class and I have read a few textbooks in addition to consolidate my study. BUT i'm a bit confused as to which explanation to trust; is it one which explains doping in terms of the band structure of the semi-conductor or how the atoms interact in a lattice as a result? In one book it refers to 'dopant' and acceptor levels from which conduction occurs as this is where the electrons jump to from the valence shell (where they leave 'positive' holes). However, most explanations just discuss the complete atom arrangement where electrons from neighbouring Si/Ge atoms try and fill the positive whole gap formed by the doped element. This then constitutes a moving charge and so, current.

Obviously both explanations make sense, but since there's a focus on band theory in the initial content leading explaining valence and conduction bands, should I stick with the band structure explanation? Which one is expected in the HSC?

Please let me know if this question doesn't make any sense!

Any help would be greatly appreciated