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kheir

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i have a test in two days and hve a few quest
1 is current a measure of drift velocity if so plz xplain i just dnt get it
2 do you have t know how a transistor works , cnt c it in syllabus
3are phonons positive if no then why do they make it possible for a cooper pair to form despite both being negative
4 and some one plz explain how diid einstein contrbute to understandinf of blakbody plz dont mix with quantum theory.

thats it for now thnx
 

Constip8edSkunk

Joga Bonito
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1 is current a measure of drift velocity if so plz xplain i just dnt get it
current is a measure of charge passing through a particular pt in a specific amount of time, ie. I = q/t (1 amp is eqivalent to 1 coulomb passing through per second. [drift velocity is related to current but also to the current density and the wires volume, the specifics has been cut from the hsc course]

2 do you have t know how a transistor works , cnt c it in syllabus
you need to know what transistors do, what they are made of, what impacts they made on society and how it was developed. exactly how it works is not required...knowing that it could be npn or pnp and that the small change at the base allows a larger amplified current to flow through an external circuit between emmitter and collector is more than enough

3are phonons positive if no then why do they make it possible for a cooper pair to form despite both being negative
phonons are packets of accoustic energy resulting from the vibrations within the metallic lattics (u can think of them as being composed of positive ions) they create localised positive areas or "troughs" as the first electron pass (look at the diagram in 1 of the text books ....i think it was either contxts or jacaranda, showing the distortion of the lattics). as the lattice reverts back into its equilibrium position, the 2nd electron is drawn into the positve "trough" and is hence is "pulled" through, absorbing the phonon energy. Hence the cooper pair is constantly being pulled apart and together through the nterchange of phonon energy, bypassing inherent resistances of conduction

4 and some one plz explain how diid einstein contrbute to understandinf of blakbody plz dont mix with quantum theory.
you cant really say more about black body rasiation, instead talk how he used planck's theory and generalised its applications. talk about how he theorised the particle model of light. make reference to his explaination of the photoelectric effect (all text books should have heaps on these points)

hope that helps
 

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