OCR Gateway Physics P4P5P6 - 18/06/13

Can someone please explain to me transistors I don't get them I have read the revision guide a million times and I dont undersatnd why they are useful please help me :frown:

Transistors are basically switches that are controlled by electricity, and they are more useful because they are much smaller than a manual switch, and you can easily put it into circuit boards, leading to smaller devices and circuits (miniaturisation).

Reply 361

L'Evil Fish

OP

18

Original post by NatashaG

Can someone please explain to me transistors I don't get them I have read the revision guide a million times and I dont undersatnd why they are useful please help me :frown:

No voltage = No current passes through

Small voltage = gate closes, current passes through

Big voltage = damage

They're used to.make logic gates as well..

Reply 362

Mutleybm1996

19

Could someone do a low-down on what's came up in the last few papers please? My computer is taking ages to download just one paper -.- :/ thanks

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Reply 363

Mutleybm1996

19

Original post by BP_Tranquility

Yeah, same here! Still can't believe that the atom model we're taught in schools for years is "obsolete" though lol :rolleyes:

...Hopefully A Levels won't have be like this :biggrin:

What do you mean they're obsolete?
(I know what Obsolete means...just wondering what you mean by it in terms of the model)

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Reply 364

Mathangi

9

Original post by BP_Tranquility

Yeah, same here! Still can't believe that the atom model we're taught in schools for years is "obsolete" though lol :rolleyes:

...Hopefully A Levels won't have be like this :biggrin:

I know someone who did Chemistry at uni and apparently they tell them to forget everything they learnt about it at A Levels because it's completely different too haha.

My chemistry teacher says it's a bit like driving a car. First you need to learn how to drive the car (GCSE) and then you're taught how the car drives.

Reply 365

NatashaG

11

Original post by Knowing

Transistors are basically switches that are controlled by electricity, and they are more useful because they are much smaller than a manual switch, and you can easily put it into circuit boards, leading to smaller devices and circuits (miniaturisation).

Original post by L'Evil Fish

No voltage = No current passes through

Small voltage = gate closes, current passes through

Big voltage = damage

They're used to.make logic gates as well..

Thanks

So like they allow things to switch on without you pressing a switch is this the right idea?

Reply 366

Elcor

14

Original post by BP_Tranquility

...Hopefully A Levels won't have be like this :biggrin:

Apparently they are, once you do a degree in a subject you took at A Level you'll see that most of the stuff wasn't detailed enough, and as you go through each year in uni you find the stuff you learned the previous year still wasn't completely right. That's just what I've heard though :colondollar:

Reply 367

Elcor

14

Original post by benwalters1996

Could someone do a low-down on what's came up in the last few papers please? My computer is taking ages to download just one paper -.- :/ thanks

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This is the first time this specification has been sat...

Reply 368

BP_Tranquility

5

Original post by benwalters1996

What do you mean they're obsolete?
(I know what Obsolete means...just wondering what you mean by it in terms of the model)

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I'm glad you asked- the model we're taught at school is called the Bohr model and it is outdated. We're taught that electrons orbit the nucleus of an atom which have circular orbits, but it is actually much more complicated than that because you can't predict both the speed the electron is travelling at and its position at the same time (since it violates the Heisenberg Uncertainty Principle). The Bohr Model was also created and its predictions are based on Hydrogen (which only has one electron) so its predictions for larger atoms that have more than one electron aren't completely accurate! Essentially, this model has now been replaced by Quantum Mechanics which provides the best explanation/predictions so far :cool:

Reply 369

L'Evil Fish

OP

18

Original post by NatashaG

Thanks

So like they allow things to switch on without you pressing a switch is this the right idea?

Yeah, I guess :smile:

use voltage instead to turn on and off

Reply 370

Mutleybm1996

19

Original post by andersson

This is the first time this specification has been sat...

Previous spec

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Reply 371

BP_Tranquility

5

Original post by cameron262

I know someone who did Chemistry at uni and apparently they tell them to forget everything they learnt about it at A Levels because it's completely different too haha.

My chemistry teacher says it's a bit like driving a car. First you need to learn how to drive the car (GCSE) and then you're taught how the car drives.

Original post by andersson

Apparently they are, once you do a degree in a subject you took at A Level you'll see that most of the stuff wasn't detailed enough, and as you go through each year in uni you find the stuff you learned the previous year still wasn't completely right. That's just what I've heard though :colondollar:

So, we have to constantly relearn new things? Well...I guess that's better than just knowing the wrong information... :tongue:

Oh well, it should be fun (hopefully) :cool:

Reply 372

Mutleybm1996

19

Original post by NatashaG

Thanks

So like they allow things to switch on without you pressing a switch is this the right idea?

'So they like turn things on and off' <---can just imagine the response to the 6 mark question now :wink:

*cheeky grin*

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Reply 373

NatashaG

11

Original post by benwalters1996

'So they like turn things on and off' <---can just imagine the response to the 6 mark question now :wink:

*cheeky grin*

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HAHA...what does a resistor do? it like makes the bull dim and stuff
Explain how gamma radiation is used to treat cancer? it like kills the cancer and stuff

I'm great at thorough explanations!!!