Physics marathon (hsc) (3 Viewers)

RishBonjour

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Question: In your studies at school, you have performed an investigation to model the behaviour of semiconductors, outline this experiment (5marks)
we used an ice cube mould. One layer was the valence band the other was the conduction band. Marbles were used to represent electrons. It was noted that when an electron migrated from the valence band to the conduction band, it left behind an employ space, that is , a positive hole. Also, when an electron moved from left to right to occupy this hole, the hole "moved" to the left.
 

dawooddaman

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Could we just re-state the Meisner effect for this experiment as it uses semiconductors?
Think superconductors and semiconductor are split into two different Dotpoints for a reason.

If you need an easy one, egg carton will do :)
 

RishBonjour

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Prior to 1947, the invention of the world's first transistor, a big problem in communication technology was amplification, the received signals were extremely weak and could not produce a loud sound without being amplified. Another problem was the short comings with valves (unreliable, high power consumption, size and warm up time), therefore the need to replace valves were brought about, not only because of the limitations of vlaves but also because of the high demand for communication technology. Therefore research into the properties of semiconductors rose in attention.

Pretty much a remember it history dotpoint
It is certainly a regurgitating dot point, but I would also add the WW2 short comings in technology. Mobile communciation devices were required for pilots to contact base towers, but thermionic devices were bulky and required significant power to operate and thus more funds were directed towards research into semiconductors. Also, radios were bulky as fk and portable radios were required--> research. Also, with communication technologies getting more and more complex, the overall efficiency of the system was increasing due to the inherent limitations of thermionic devices (heat dissipation, starting time lag, bulky, fragile)--> research towards semi conductors and transistors.
 

freeeeee

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Think superconductors and semiconductor are split into two different Dotpoints for a reason.

If you need an easy one, egg carton will do :)
Ye the egg carton one works nice or marbles in a preti dish, you have to talk about movement of holes and electrons as well as how this was simulated in your experiment including a diagram, relating this back to semiconductors to get 5marks.
 

barbernator

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Question: In your studies at school, you have performed an investigation to model the behaviour of semiconductors, outline this experiment (5marks)
I would talk about the inertial and non-inertial frames of reference experiment.
 

freeeeee

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Question: How did the Braggs determine the crystal structure of a lattice? and what impact did it have on the scientific understanding of metal lattices (4marks)
 

deswa1

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A calculation question to get everyone on their game:

 
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Yes that is what i got
Firstly using T=BANIcostheta
To find current

Then further using F=BIL on side AB

Hence we get 1.6N
 

barbernator

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C it is. That being said, the effing motor has 3 turns on one side and 4 on the other, so poor question is poor lol.
 

2xL

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you didnt need to count turns, they will cancel out as you use both formulas,
Indeed it does. Good job. Can just find "nI" together and substitute into force. (Y)
 

RishBonjour

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Question: How did the Braggs determine the crystal structure of a lattice? and what impact did it have on the scientific understanding of metal lattices (4marks)
Since X-rays have extremely short wavelength, Braggs though that by subjecting a crystal structure to X-ray beams information about lattice structure could be gathered. They used an X-ray tube to emit uniform X-ray beams through collimators towards the lattice structure so they remained parallel as they hit the plane. These X-rays were reflected by different lattice planes and some were detected by the detector. These resulted in an interference pattern which the Braggs analysed mathematically (don't think the whole equation is necessary) to find the distance between the planes. This was repeated from different orientation and the same distance was found, suggesting a uniform 3D pattern.

I think:
This discovery helped us better understand how conduction occurred --> electrons flow between lattice planes in metals. Also, improved scientific understanding on resistance --> lattice could obstruct electrons. It also enabled more understanding into doping by enhancing scientist's understanding of crystal structures?



btw: Any other projectile motion question like that electron one ?
 

freeeeee

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Do we need to know some metals/alloys/ceramic that exhibit superconducting properties and their critical temperatures? or in a question do they give this info to us?
 

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i have my notes but i'm still scared. re summarising to remember and then tomorrow i'm gonna highlight the important stuff and then start re writing those. Is that a good idea?
 

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