# Resistivity and temperature coefficients

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#1
Hi, im stuck on Ex 20.3 question 2.

I tried workibg out the resistivity at 0 degrees c. Then i substituted that back into the formula and i got an answer 1.53*10^-7 ohm metres.

The book says the answer is 18*10^-8 ohm metres.

I cannot figure out where i went wrong.

I will post my working and the question below.

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#2
I forgot to write down the power in the second stage of working out hoever i used the actual correct value in my calculator when doing the calculationsAttachment 635982635984
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3 years ago
#3
The temperature coefficient formula is given by the resistivity at reference temperature multiplied by (1 + coefficient(change in temp)); so, using that, the new resistivity will be (15E-8)(1 + 40(50E-4)) = 18E-8

I don't know about the formula side, I just used the formula google gave me for this. I can only qualitatively describe resistivity to you, but that's how you get the answer they gave you. I'll put the formula for you below.

If you didn't know that formula or anything, then it isn't your fault. If there is another method, I can't help, I've not done that sort of thing before; what's that other formula? o,O
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#4
That formula can be used for resisitivity too, just sub in resisitivity for resistance.

The way my book had the formula laid out said that the resistance at the reference point was always the resistance at 0 degrees celsius.

Guess the book couldve been a bit clearer. In hindsight i lrobz shoulve googled it myslef but hey hindsight is 20/20.

Thanks for ur help man
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3 years ago
#5
(Original post by Shaanv)
That formula can be used for resisitivity too, just sub in resisitivity for resistance.

The way my book had the formula laid out said that the resistance at the reference point was always the resistance at 0 degrees celsius.

Guess the book couldve been a bit clearer. In hindsight i lrobz shoulve googled it myslef but hey hindsight is 20/20.

Thanks for ur help man
No problem, helping people allows my procrastination from my own revision to grow stronger, after all.
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#6
What u revising for. Ive got 6 real maths a level exams this year as im doing edexcel firther maths, and i got 2 physics and 2 chem mocks this year.
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3 years ago
#7
(Original post by Shaanv)
What u revising for. Ive got 6 real maths a level exams this year as im doing edexcel firther maths, and i got 2 physics and 2 chem mocks this year.
Well, last year I didn't do any work, we're talking at all, so, redoing my D1 and C2 exams. This year I've been semi-sweaty, so picking up the sweat now

Revising for:
C3, C4, M1, C2, D1 math exams
AQA Physics A2 w/ Turning Points
Biology EDUQAS w/ Musculoskeletal Anatomy

That's pretty much it :P

Are you an AS or A2 student? I'm guessing AS since you're doing the mocks (on the new spec I presume, from what my teacher say it's painful)
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#8
Im an AS student and im on the new spec. Initially we started chapter 1 with a teacher and the mechanics section with another teacher.

The mechanics was extremely hard at the start trying to learn the content and understand it, as our teacher was of very little help. So far for the AS spec the most challenging concepts are waves and electricity, i especially hate waves with a passion.

The lack of past papers for the spec is worrying me most, as for maths ive just been doing past paper after past paper to revise and i wont be able to do that with physics.

Speaking of maths, the c3 papers are messing me over i swear the papers are getting exponentially harder every year.

Also if ur on edexcel maths how was d1. Easy?
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3 years ago
#9
(Original post by Shaanv)
Im an AS student and im on the new spec. Initially we started chapter 1 with a teacher and the mechanics section with another teacher.

The mechanics was extremely hard at the start trying to learn the content and understand it, as our teacher was of very little help. So far for the AS spec the most challenging concepts are waves and electricity, i especially hate waves with a passion.

The lack of past papers for the spec is worrying me most, as for maths ive just been doing past paper after past paper to revise and i wont be able to do that with physics.

Speaking of maths, the c3 papers are messing me over i swear the papers are getting exponentially harder every year.

Also if ur on edexcel maths how was d1. Easy?
I found D1 quite easy, as with everything else to be honest (not to sound like a bum or anything :_ but the problem for me was mentality: I'm pretty stressed out all the time. It will just depend on your own mentality, the content itself isn't hard, it's whether or not you have the type of mindset to process it. C3 is a bummer compared to C4, and M1 just rehashes Mechanics.

Physics past papers are plentiful! Use the 'Old Spec' AQA papers. They're similar to the new spec and are more challenging. I have a book titled 'University Physics' (quite cheap, I got it for £30 on Amazon, and since you're an AS it will be more useful for you, trust me, in A2 it really is :P) and it's quite good. I'd recommend getting any undergraduate textbook on Physics: the questions are similar to ours, stupendously similar, with worked examples. Physics and Math Tutor have loads of papers from OCR and WJEC, some of which are quite good. Trust me when I say this, any practice, even repetitive practice, ends up helping a little.

When you get to A2, you'll really love Electromagnetism. Fills in plenty of gaps, but is painal on a stick at times. If you ever need help with any AS stuff, hit me up ;p
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#10
Ive got me a couple of calculation books for a level physics, my main problem is the worded questions they always mess me over. Most of my calculation is pretty good since 70% of my studying time this year has gone to getting my 6 modules done for maths.
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3 years ago
#11
(Original post by Shaanv)
Ive got me a couple of calculation books for a level physics, my main problem is the worded questions they always mess me over. Most of my calculation is pretty good since 70% of my studying time this year has gone to getting my 6 modules done for maths.
6 modules? Yikes! I only had to do C1, C2, and D1 :P
That explains why you mentioned C3 in AS.

I'd say that the worded ones are annoying, but not impossible. I cheat a little because I can type my exams, so, makes things interesting. If you have to write them out, then hitting every marker is difficult, as examiners expect you to milk every last bit of detail.
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#12
I bit off a good amount of work for my two years just with maths.
6 modules in each year grand totalling to two a levels in maths with the physics and chem ones on top provided i make it that far.

Are u planning on going to uni? If so what courses and unis are u looking at?

Me personally im thinking of doing some kind of engineering degree.
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3 years ago
#13
(Original post by Shaanv)
I bit off a good amount of work for my two years just with maths.
6 modules in each year grand totalling to two a levels in maths with the physics and chem ones on top provided i make it that far.

Are u planning on going to uni? If so what courses and unis are u looking at?

Me personally im thinking of doing some kind of engineering degree.
If you're doing Engineering, see about doing the Engineering in your course (if you do AQA, if another spec, no clue if you can :P) since it has stuff relevant.

I'm going to do Astrophysics, hopefully in Edinburgh. My godfather (Soviet Godfather, much wow) teachers all sorts of stuff at the Uni
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#14
Nice, good luck with everything in the future.

I had wanted to do the engieering in the physics course next year however it was a class decision and i got outvoted for astrophysics because our teacher couldnt be bothered to learn and prepare lessons for us, so thats always fun.

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3 years ago
#15
(Original post by Shaanv)
Nice, good luck with everything in the future.

I had wanted to do the engieering in the physics course next year however it was a class decision and i got outvoted for astrophysics because our teacher couldnt be bothered to learn and prepare lessons for us, so thats always fun.

AAA, which considering the course, isn't too bad.

You lucky duck! Well, relatively speaking. I was outvoted for Turning Points. Hell, not even a vote, the teacher said (as great as she is) that it's easier to sort out because we've covered quite a bit already.
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#16
Our teacher said turning points was loads of writing ive never seen people change there minds so fast in my life.

Im hoping that my shortfall in not being able to do engineering in physics will be offset by the fact that im probz gonna do M1, M2 and M3.
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3 years ago
#17
(Original post by Shaanv)
Our teacher said turning points was loads of writing ive never seen people change there minds so fast in my life.

Im hoping that my shortfall in not being able to do engineering in physics will be offset by the fact that im probz gonna do M1, M2 and M3.
Again, lucky son of a cluck. I'd toss away D1 if it meant M2 and M3! :_:

Yeah, Special Relativity, Spacetime, all that Einstein business. I love it xD
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#18
My maths teacher is a 65 year old man yet he is the most flexible man you will ever meet.

Literally i could turn around to him and tell him im doing m1-5 and he would say good luck and let me get on with it.
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3 years ago
#19
(Original post by Shaanv)
My maths teacher is a 65 year old man yet he is the most flexible man you will ever meet.

Literally i could turn around to him and tell him im doing m1-5 and he would say good luck and let me get on with it.
o,o

Ours is a rock climbing young doctorate-holding fellow, he's splendid, yet stern
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