HSC Physics Question Thread

[jamonwindeyer]

hi again! So I'm starting to get confuse: is a Solid State Device a fancy name for a transistor? (are they the same thing?) I have to  talk about the invention of the transistor
Thanks

And PN diodes are ssd's as well!

[Yagami Light]

Thanks guys keep up the work

[Bubbly_bluey]

Hi! What does it mean to discuss the possible future applications of superconductivity of development of the maglev train, supercomputers and electricity transmission? I just thought that they were already the applications of the superconductor, if you know what I mean.
Thank you

[pikachu975]

Hi! What does it mean to discuss the possible future applications of superconductivity of development of the maglev train, supercomputers and electricity transmission? I just thought that they were already the applications of the superconductor, if you know what I mean.
Thank you

Maglev train isn't used everywhere in the world with superconductors. I can't really remember but either Japan or Germany use superconductors for their maglev trains and it's really hard because you have to cool the whole track. There's still lots of improvements to be made.

Supercomputers I haven't researched.

Electricity transmission doesn't use superconductors yet. Superconductors have zero electrical resistance when cooled below critical temperature so in the future they can be used to eliminate power loss altogether as Ploss = I^2 R and R = 0. Hasn't been used yet because I think it's be too costly to cool all transmission lines for now.

[Bubbly_bluey]

Maglev train isn't used everywhere in the world with superconductors. I can't really remember but either Japan or Germany use superconductors for their maglev trains and it's really hard because you have to cool the whole track. There's still lots of improvements to be made.

Supercomputers I haven't researched.

Electricity transmission doesn't use superconductors yet. Superconductors have zero electrical resistance when cooled below critical temperature so in the future they can be used to eliminate power loss altogether as Ploss = I^2 R and R = 0. Hasn't been used yet because I think it's be too costly to cool all transmission lines for now.

Oh thanks so much! So by "future applications" would I have to  mention the limitations and suggest improvements for each application?

[jakesilove]

Oh thanks so much! So by "future applications" would I have to  mention the limitations and suggest improvements for each application?

Yeah pretty much! I would subheading like 'Supercomputers', 'Motors and generators', 'Power distribution' etc. then talk about how superconductors would benefit that technology, as well as potential limitations (eg Superconductors can only transmit DC, requires huge amounts of energy to keep below critical temperature etc.)

[beau77bro]

we have an assessment tuesday, its a speech on transistors:

we need to - say who developed the transistor,
- what they are
- how they work
- provide a brief timeline
- impacts of the development on society (+ve and -ve and how society has changed)
- how germanium was used due to a lack of availability
- describe difference in thermionic and solid state
- say why solid state replaced thermionic
- current research - and further questions to be answered

in 7 minutes - as well as providing an intro and conclusion - so somehow i need to get my 1150 words to like 900-1000. COULD YOU GUYS PLEASE READ THIS AND HIGHLIGHT ANY INFO YOU THINK ISNT NECESSARY - i need to cut down a lot
 - cut doe coz i already got rid of the cool facts and extra info that made it interesting.
btw - green is like should i cut or nah?

i was also gonna add quantum computing:

Spoiler

Now we say the electron spin is pointing, up or down or anywhere in between. This is important because in classical computers we have up or down, on or off, a switch which determines 1s or 0s. But here we have electrons that can be in two possible states at the same time, meaning it can solve things exponentially faster, because as you add more quantum bits the processing power doubles. THAT IS RIDICULOUS. In your phone you have over a billion transistors, but take out your calculator and type in 2 to the 100, not billion, a hundred and it has well past the capability of your phone.
Basically the outer most electron of a phosphorus atom in a silicon chip can have information placed on it by rotating it’s spin with microwaves, as well as the spin of it’s nucleus. It’s really complicated and awesome, if you wanna know more about it there are great videos by veritasium, and there’s a whole list on the handout.

but i cant coz no space

sorry for long post - THANKYOU

Mod Edit: Added spoiler

[jamonwindeyer]

we have an assessment tuesday, its a speech on transistors:
...

Hey! I had a peek and highlighted some stuff in yellow I'd remove (all the stuff in green, ditch it imo).

If you trim what I trimmed, then cut back the explanation of the Quantum Physics stuff at the end (see the comment inside, you need to consider the audience you are speaking to!), you should have room to put a brief explanation of Quantum Computing, and still be under 1000 words

[bluecookie]

How does this work?

http://www.a-levelphysicstutor.com/images/fields/E-fields-unif.jpg

Because in yr 11 we were taught that a circuit must be connected to allow current to travel through it, but in this one there's no connection between the two plates? So how does electricity flow through them?

[jakesilove]

How does this work?

http://www.a-levelphysicstutor.com/images/fields/E-fields-unif.jpg

Because in yr 11 we were taught that a circuit must be connected to allow current to travel through it, but in this one there's no connection between the two plates? So how does electricity flow through them?

You're totally right to question this; it isn't something that's properly looked at in the HSC! Basically, a device like this is called a capacitor (you don't need to know this). The plates get 'charged up', and eventually have so much energy in them that they 'discharge', completing the circuit. The electrons essentially 'jump' the gap between the two plates, because whilst they really don't like to, electrons are capable of travelling through air. So, you can imagine that the circuit is (weakly) complete by the air between the plates, which the electrons are sometimes able to flow through.

In the HSC, you don't need to know any of this; you're just supposed to assume that the situation is all g. Really good question though. I haven't given you a huge amount of depth, because there's no point over complicating your HSC Physics course, but let me know if you have any more questions or if I can clarify anything!

[bluecookie]

You're totally right to question this; it isn't something that's properly looked at in the HSC! Basically, a device like this is called a capacitor (you don't need to know this). The plates get 'charged up', and eventually have so much energy in them that they 'discharge', completing the circuit. The electrons essentially 'jump' the gap between the two plates, because whilst they really don't like to, electrons are capable of travelling through air. So, you can imagine that the circuit is (weakly) complete by the air between the plates, which the electrons are sometimes able to flow through.

In the HSC, you don't need to know any of this; you're just supposed to assume that the situation is all g. Really good question though. I haven't given you a huge amount of depth, because there's no point over complicating your HSC Physics course, but let me know if you have any more questions or if I can clarify anything!

Thanks for the fast response It helped clarify a lot!

[jakesilove]

Thanks for the fast response It helped clarify a lot!

Glad it helped Great job picking up on something that I don't think I've ever thought about in the HSC context, and I don't think has ever been asked on the forums!

[Aaron12038488]

how hard is the motors and generators topic for hsc?
is it similar to Electricity in home?

[jamonwindeyer]

how hard is the motors and generators topic for hsc?
is it similar to Electricity in home?

I'd say it is a little harder, there are some trickier concepts to grasp in there to compared to the Year 11 Topic

There is some crossover, and some required Y11 knowledge to really get the Year 12 stuff, but the two are pretty much completely different

[bluecookie]

Consider the movement of 1C of positive charge in a uniform electric field as shown below.

(Just a diagram of a plate with the positive plate at the top, and a positive charge placed in the field at the top, and then moving towards the bottom. No numerical values given for d, or v; they're just labelled as the letters).

The question states: Compare the kinetic energy of the Coulomb of charge at the top plate to the kinetic energy of the charge right before it collides with the bottom plate.

Halllp. How do you find the kinetic energy in terms of electricity?