Physics marathon (hsc) (5 Viewers)

[nerdasdasd]

Post questions and everyone shall answer them . Let's see what we all know .

 

[J-Wang]

Post questions and everyone shall answer them . Let's see what we all know .

What are transistors/ how do they work/ what do we need to know about them?

 

[oh well]

do we needa know forward biased and shiz?

 

[nerdasdasd]

What are transistors/ how do they work/ what do we need to know about them?

Transistors are amplifying devices that are composed primarily of semiconductors. We need to know the impact of their development, e.g. lead to the microprocessor, computer age, increased people's living standards. etc.

 

[nerdasdasd]

do we needa know forward biased and shiz?

Nah, don't think so.

 

[deswa1]

Transistors- small switches that can control or amplify the current etc. Were invented in response to crap communications technology (the thermionic devices)- you can BS about all their advantages etc. Made of semiconductors (n-type and p-type -> BS here). There are two types, PNP and NPN- not sure if you need to know how to draw them but I do just in case. They work by forming an electric diffusion field between the PN junctions, which depending on whether the transistor is forward or reverse biased, can control direction flow etc. Integral component of integrated circuits and microchips -> BS about the impacts on society.

Obviously in a test I would draw diagrams/explain things better but I think this is the general thing you need to know about transistors- I might have missed stuff (just did this off the top of my head so please tell me if I did, or gone into details that you don't really need)

 

[nerdasdasd]

Transistors- small switches that can control or amplify the current etc. Were invented in response to crap communications technology (the thermionic devices)- you can BS about all their advantages etc. Made of semiconductors (n-type and p-type -> BS here). There are two types, PNP and NPN- not sure if you need to know how to draw them but I do just in case. They work by forming an electric diffusion field between the PN junctions, which depending on whether the transistor is forward or reverse biased, can control direction flow etc. Integral component of integrated circuits and microchips -> BS about the impacts on society.

Obviously in a test I would draw diagrams/explain things better but I think this is the general thing you need to know about transistors- I might have missed stuff (just did this off the top of my head so please tell me if I did, or gone into details that you don't really need)

Band 6 answer ^.

 

[nightweaver066]

Transistors- small switches that can control or amplify the current etc. Were invented in response to crap communications technology (the thermionic devices)- you can BS about all their advantages etc. Made of doped semiconductors (n-type and p-type -> BS here). There are two types, PNP and NPN sandwich structures- not sure if you need to know how to draw them but I do just in case. They work by forming an electric diffusion field (are you talking about the depletion layer? I haven't heard of it being called that) between the PN junctions, which depending on whether the transistor is forward or reverse biased (how? By applying +/- potential to the base), can control direction flow etc. Integral component of integrated circuits and microchips (should include microprocessors here. It's mentioned in the dot point) -> BS about the impacts on society.

Obviously in a test I would draw diagrams/explain things better but I think this is the general thing you need to know about transistors- I might have missed stuff (just did this off the top of my head so please tell me if I did, or gone into details that you don't really need)

Just added a few things and commented. Probably are things that you already knew, but just putting it out there

 

[lemon1]

more questions!

 

[deswa1]

Assume that the Earth rotated slower than it does currently. Predict what would happen to the value of g (gravitational acceleration) at:

a) The equator
b) The poles

 

[nerdasdasd]

Assess the impact of advances of knowledge about superconductors and semiconductors on the development of MRI (7 marker).

 

[iSplicer]

Transistors- small switches that can control or amplify the current etc. Were invented in response to crap communications technology (the thermionic devices)- you can BS about all their advantages etc. Made of semiconductors (n-type and p-type -> BS here). There are two types, PNP and NPN- not sure if you need to know how to draw them but I do just in case. They work by forming an electric diffusion field between the PN junctions, which depending on whether the transistor is forward or reverse biased, can control direction flow etc. Integral component of integrated circuits and microchips -> BS about the impacts on society.

Obviously in a test I would draw diagrams/explain things better but I think this is the general thing you need to know about transistors- I might have missed stuff (just did this off the top of my head so please tell me if I did, or gone into details that you don't really need)

Nice answer deswa, but a few technical glitches. About to go to bed so will pick out the first one that could cost you a mark - transistors aren't really switches per se. They are a device that CAN be used as switches, as well as the amplification of current. Also, they aren't necessarily small (what is 'small' anyway - you'd need to qualify that). You definitely need to know how to draw NPN and PNP.

But yes, I'm sure you knew all that already (as you said that it was off the top of your head, late at night, etc), but just pointing it out to others as a means of procrastinating for my test on Monday =).

 

[jax447]

Assume that the Earth rotated slower than it does currently. Predict what would happen to the value of g (gravitational acceleration) at:

a) The equator
b) The poles

a) decreased
b) the same

This exact question came up in the trials and both 'increased' and 'the same' were accepted as answers for part b).

My school is stupid.

 

[RishBonjour]

Assume that the Earth rotated slower than it does currently. Predict what would happen to the value of g (gravitational acceleration) at:

a) The equator
b) The poles

a) decrease due to lower "fling off" effect (centrifugal effect or something)
b) stays the same since the distance between the poles and centre mass is the same


Assess the impact of advances of knowledge about superconductors and semiconductors on the development of MRI (7 marker).
- can they ask is specifically for MRI? or is this for Med phy?

 

[deswa1]

Just added a few things and commented. Probably are things that you already knew, but just putting it out there

Nice answer deswa, but a few technical glitches. About to go to bed so will pick out the first one that could cost you a mark - transistors aren't really switches per se. They are a device that CAN be used as switches, as well as the amplification of current. Also, they aren't necessarily small (what is 'small' anyway - you'd need to qualify that). You definitely need to know how to draw NPN and PNP.

But yes, I'm sure you knew all that already (as you said that it was off the top of your head, late at night, etc), but just pointing it out to others as a means of procrastinating for my test on Monday =).

Yeah cheers- thanks guys Its good when people point out the small details imo

 

[SpiralFlex]

a) decrease due to lower "fling off" effect (centrifugal effect or something)
b) stays the same since the distance between the poles and centre mass is the same


Assess the impact of advances of knowledge about superconductors and semiconductors on the development of MRI (7 marker).
- can they ask is specifically for MRI? or is this for Med phy?

They should be able to specify.

Could we have some real physicy questions, I do not like long responses.

 

[bleakarcher]

a) decrease due to lower "fling off" effect (centrifugal effect or something)
b) stays the same since the distance between the poles and centre mass is the same


Assess the impact of advances of knowledge about superconductors and semiconductors on the development of MRI (7 marker).
- can they ask is specifically for MRI? or is this for Med phy?

Sorry, just a question. Wouldn't a decrease in rotational velocity result in a lower radius and hence an increased value of g?

 

[nerdasdasd]

They should be able to specify.

Could we have some real physicy questions, I do not like long responses.

What happens when an magnet falls down a copper tube?

 

[SpiralFlex]

What happens when an magnet falls down a copper tube?

=.= I think i'll post some questions that require a little bit of lateral thinking. ;/

 

[Kimyia]

Assume that the Earth rotated slower than it does currently. Predict what would happen to the value of g (gravitational acceleration) at:

a) The equator
b) The poles

Just curious, doesn't the rotation of the earth also cause it to bulge at the equator? So would a slower rotation speed mean the earth wouldn't bulge so much at the equator and it would be closer to the centre of the earth and increase the value of g??

Also: doesn't the 'fling' effect reduce the value of g. So if you slowed the rotation, you'd slow the 'fling' effect at the equator and again increase the value of g?