Aaargh! Physics!!

[midzt]

Hey guys,

I'm having trouble with my AS physics again. The teacher hasnt taught us anything in the two lessons we've been on the topic and she has already given us three work sheets! The CD that came with the course is bust, keeps prompting me to install Office and crashes every few minutes anyway, and the text book given to us has nothing that can help me!

So..

How do i work out the number of electrons arriving per second using Voltage, Current and Time?

Also how do i work out the energy of each electron using the same figures?

What is drift velocity?

Thanks for any help

[Skii]

www.google.co.uk

http://rkb.home.cern.ch/rkb/PH14pp/node52.html

[midzt]

Yeh I tried google but everything I searched for seemed really complicated.

I've worked most if it out now by trying combinations of all the numbers.

THanks anyway.

[aeonf242]

Yeh I tried google but everything I searched for seemed really complicated.

I thought you were doing AS level, isn't it supposed to be complicated

[GreenPiggy]

How do i work out the number of electrons arriving per second using Voltage, Current and Time?

An Amp(Current) is a coulomb per second, a coulomb is 6.2 × 10^18 electrons.
Therefore the amount of electrons arriving per second is simply the current times the number of electrons

Also how do i work out the energy of each electron using the same figures?

A volt is a joule per coulomb so the energy of each electron is Voltage divided by the number of electrons per second(above)

What is drift velocity?

It is the speed the electrons travel through a material.
It changes depending on the material.


where n is the number of electrons per cubic metre
A is the cross sectional area of the wire
v is the drift velocity of the electrons
Q is the charge of an electron

You know all of these apart from n(unless you know what material it is travelling through in which case I can find out)

[Nick]

^^ What he said....

Like I have ANY idea what all that means...

[midzt]

Thanks GreenPiggy, I've got the answers for the questions now and pretty muhc understand it aswell.

[Twigman]

I have to say Alevel physics was the only alevel that I found there was a big jump up from AS to A2...I found A2 pretty difficult and As resonably easy....just thought Id let you know...

[GreenPiggy]

The jump from A2 to university is far far worse..

[Byatt]

The jump from A2 to university is far far worse..

Quoted for truth - but due to Maths A-level as well as Physics, I reckon.

[GreenPiggy]

Yep, the Maths is by far the worst part of it

[headbrace]

Mebbe it's just me, but the maths is just plugging stuff in formulae and getting the answer, whch they often provide you with anyway. I find the tricky bit is writing the right stuff that they want in the longer questions. But, anyway, top post there Greenpiggy.

[GreenPiggy]

ah who cares, bottom line is that it's all goddam hard

[Twigman]

nah physics is mostly just plugging into equations really. Just need to know the right ones ...lol
Yeah physics and maths are cool (yes ) but hard.

[Byatt]

Mebbe it's just me, but the maths is just plugging stuff in formulae and getting the answer, whch they often provide you with anyway. I find the tricky bit is writing the right stuff that they want in the longer questions. But, anyway, top post there Greenpiggy.

And, you see, at degree level, this stops. A lot of the time at degree level new physical concepts are introduced alongside new bits of maths which you need to understand them, when really it would be more ideal to have the mathematical grounding first.

If you're not there yet...well, imagine you were trying to do this original question, but you had to learn how to multiply at the same time - a pretty crap analogy, but it's as close as you'll get.

physics and maths are cool

[GreenPiggy]

One of the classic examples being Div and Curl in thermodynamics. Still gives me nightmares