HSC Physics Question Thread

[beau77bro]

sweeeeeeetttttttttttt

[jamonwindeyer]

...  thankyouuuu, and where are the past papers hahaha sorry?

Google THSC, it should be the first option! HUGE bank of past papers and resources

[beau77bro]

oh yea, theres only a couple of half yearlies? should i just do trials if i finish them?

[jamonwindeyer]

oh yea, theres only a couple of half yearlies? should i just do trials if i finish them?

There's 10 half yearlies, that in conjunction with textbook questions should be heaps! Like, do Trials if you need to, but 10 half yearly practice papers with a few dozen textbook questions is definitely a heap of practice if you do every paper, mark it, consolidate then go back and re-answer things you got wrong - That's a solid 3-4 hours per paper, so you've got a solid 30-40 hours of study there

[bluecookie]

"A current-carrying conductor will produce its own magnetic field that can interact with an external magnetic field producing a force (the torque effect). The relative motion between an external magnetic field and a conductor will produce a current within that conductor (electromagnetic force).
When you combine these two phenomena together the current that is induced in the conductor produces its own magnetic field that will interact with the external magnetic field that produced the current in the first place!"

^^ This is what it says in my textbook. I'm a bit confused, does the current produced change direction in regards to the initial current? (is it independent of the initial current is what I'm trying to say)

And doesnt that mean the current/magnetic field are changing all the time? Cause if the current produces its own magnetic field that then interacts with the external magnetic field...that means a new current is produced. But then the production of that new current changes the initial magnetic field, which then changes the interaction with the external magnetic field, so does that mean there's a constant flow of new currents and magnetic fields when it comes to current carrying conductors?

[jakesilove]

"A current-carrying conductor will produce its own magnetic field that can interact with an external magnetic field producing a force (the torque effect). The relative motion between an external magnetic field and a conductor will produce a current within that conductor (electromagnetic force).
When you combine these two phenomena together the current that is induced in the conductor produces its own magnetic field that will interact with the external magnetic field that produced the current in the first place!"

^^ This is what it says in my textbook. I'm a bit confused, does the current produced change direction in regards to the initial current? (is it independent of the initial current is what I'm trying to say)

And doesnt that mean the current/magnetic field are changing all the time? Cause if the current produces its own magnetic field that then interacts with the external magnetic field...that means a new current is produced. But then the production of that new current changes the initial magnetic field, which then changes the interaction with the external magnetic field, so does that mean there's a constant flow of new currents and magnetic fields when it comes to current carrying conductors?

Honestly, you've nailed it. If you're confused, that's because it's confusing, but you're 100% correct. The current produces ANOTHER field, which produces ANOTHER current, which opposes the direction of the original current (Ie. it is dependant on the initial current; the induced current will run opposed to the supplied current!). And yes, things are constantly changing and shifting, however it all eventually settles down into a sort of equilibrium. I have to say, though, that you seem to understand the principle of back-emf really well! It's bloody confusing, it took quite a few goes for me to understand what was happening. Keep revising!

[bluecookie]

Honestly, you've nailed it. If you're confused, that's because it's confusing, but you're 100% correct. The current produces ANOTHER field, which produces ANOTHER current, which opposes the direction of the original current (Ie. it is dependant on the initial current; the induced current will run opposed to the supplied current!). And yes, things are constantly changing and shifting, however it all eventually settles down into a sort of equilibrium. I have to say, though, that you seem to understand the principle of back-emf really well! It's bloody confusing, it took quite a few goes for me to understand what was happening. Keep revising!

Thank you

[bluecookie]

What are hyperfine and fine levels in the atomic clock caesium-133?

When they say the electron moves is excited and moves from one energy level to another, does the electron move from the first energy level to the second and then back? Or does it move from the first to the last energy elvel and then back? Or is it random movement in either direction?

Also, when they say one second is defined by the duration of [inset number I can't be bothered to type haha] periods of radiation corresponding to the transition between two hyperfine levels, what is one period defined by? Is it the one singular jump between energy levels? Or is one period defined by the jump from the inner energy level to the outer? (if it orbits in that way)

Sorry, just really confused

[jamonwindeyer]

What are hyperfine and fine levels in the atomic clock caesium-133?

When they say the electron moves is excited and moves from one energy level to another, does the electron move from the first energy level to the second and then back? Or does it move from the first to the last energy elvel and then back? Or is it random movement in either direction?

Also, when they say one second is defined by the duration of [inset number I can't be bothered to type haha] periods of radiation corresponding to the transition between two hyperfine levels, what is one period defined by? Is it the one singular jump between energy levels? Or is one period defined by the jump from the inner energy level to the outer? (if it orbits in that way)

Sorry, just really confused

Hey hey! While someone a little more rehearsed (like Jake) might be able to help you here, just know that you definitely don't need to know how an atomic clock works in the HSC is this as background knowledge for the time dilation section in Space? You will never be expected to explain how an atomic clock works

Edit: Woops unless this is from an Option in which case ignore me and hopefully Jake can help you out!

[bluecookie]

Hey hey! While someone a little more rehearsed (like Jake) might be able to help you here, just know that you definitely don't need to know how an atomic clock works in the HSC is this as background knowledge for the time dilation section in Space? You will never be expected to explain how an atomic clock works

Edit: Woops unless this is from an Option in which case ignore me and hopefully Jake can help you out!

Ah sorry, my bad. It was extension work the teacher gave us. ^^

[jakesilove]

What are hyperfine and fine levels in the atomic clock caesium-133?

When they say the electron moves is excited and moves from one energy level to another, does the electron move from the first energy level to the second and then back? Or does it move from the first to the last energy elvel and then back? Or is it random movement in either direction?

Also, when they say one second is defined by the duration of [inset number I can't be bothered to type haha] periods of radiation corresponding to the transition between two hyperfine levels, what is one period defined by? Is it the one singular jump between energy levels? Or is one period defined by the jump from the inner energy level to the outer? (if it orbits in that way)

Sorry, just really confused

Hey! I'm only going to answer your second question, because the other two are DEFINITELY way outside the curriculum. The second, however, can form a part of the Q2Q option, and is also not too difficult to explain.

You can imagine that light, of a certain energy/wavelength, is incident on an electron in the first energy level. The electron will absorb that energy if and only if it is the exact energy required to pump it up a certain number of discrete energy levels. So, say the difference in energy between n=1 and n=2 was 10kJ, and n=2 and n=3 was 15kJ. Then, a photon with 10kJ of light could cause an n=1 electron to go to n=2 (and back), but not an n=2 to n=3. Similarly, a photon with 25kJ of energy could cause an n=1 electron to go to n=3 (and back).

Note that there isn't a 'last' energy level.

Hope that explanation makes sense!

[bluecookie]

Hey! I'm only going to answer your second question, because the other two are DEFINITELY way outside the curriculum. The second, however, can form a part of the Q2Q option, and is also not too difficult to explain.

You can imagine that light, of a certain energy/wavelength, is incident on an electron in the first energy level. The electron will absorb that energy if and only if it is the exact energy required to pump it up a certain number of discrete energy levels. So, say the difference in energy between n=1 and n=2 was 10kJ, and n=2 and n=3 was 15kJ. Then, a photon with 10kJ of light could cause an n=1 electron to go to n=2 (and back), but not an n=2 to n=3. Similarly, a photon with 25kJ of energy could cause an n=1 electron to go to n=3 (and back).

Note that there isn't a 'last' energy level.

Hope that explanation makes sense!

Thank you!

[imda.beast]

Hi, I want to know how should I answer "Identify a rocket scientist and assess two of his major contributions to rocketry" for Von Braun, since most of von Brauns work is practical based rather than theory based, I find it difficult to assess his contribution. Thnx jake

[jakesilove]

Hi, I want to know how should I answer "Identify a rocket scientist and assess two of his major contributions to rocketry" for Von Braun, since most of von Brauns work is practical based rather than theory based, I find it difficult to assess his contribution. Thnx jake

Hey, and welcome to the forums! Doesn't matter whether his contribution is practical or theory, as long as you list two of them. For instance, if you cited the development of the Saturn V rockets, and various shuttle engineering developmenets, that would be plenty, as long as you assess the contributions as well (eg. Saturn V took us to the moon!).

[Aaron12038488]

I know I've asked this question before. I'm having trouble with this dot point: Describe ways in which applications of reflection of light, radio waves and microwaves have assisted information transfer. What do I write for Light and Microwaves.
Thanks