Qualification > Sciences

Physics P5, HELP!

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Twinkle Charms:

--- Quote from: aorta on June 08, 2010, 08:40:39 pm ---It says in the question that the student is given sheets of glass of different areas.

'Independent variable' is something that you can vary, which the 'dependent variable' depends on..

So here, you can varying the the area of the glass will have an effect on the resistance, therefor R depends on A.

So R is the dependent.. and  A the independent..

Hope you understood what I mean :)


--- End quote ---
so why dont we consider the lenght?

aorta:

--- Quote from: Zara on June 08, 2010, 08:42:57 pm ---so why dont we consider the lenght?

--- End quote ---

Hmm, I'm not really sure. Maybe because in the question, it says we are given sheets of glass of different areas and same thickness. So I guess we should just assume that they have already varied the length and got different areas.

I think that it's pretty much the same thing.

Actually, lets say that you are the student, you are given 5 glasses of different areas, and each glass has it's area written on it. So you'll just use the different areas, why bother to vary the length and then get a different area when it's already done for you.

So you just use them..  I think.

aorta:
Okay, M/J 2008, question 2 part a. How do you find the gradient and y-intercept??

I almost never get them right!

nancy:
guys it says- USE RHEOSTAT to keep current constant?

how do you do that???

falafail:

--- Quote from: aorta on June 08, 2010, 08:57:42 pm ---Okay, M/J 2008, question 2 part a. How do you find the gradient and y-intercept??

I almost never get them right!

--- End quote ---

rearrange the equation to give you y = mx + c
here you get ln R = ln Ro - pnx ln e
ln e = 1
so ln R = -pn x  + ln Ro
-pn is the gradient and ln Ro is the y-intercept


--- Quote from: nancy on June 08, 2010, 08:59:46 pm ---guys it says- USE RHEOSTAT to keep current constant?

how do you do that???

--- End quote ---
yeah i don't get that either :/


Zara, i tried doing that question but i really don't get it  :-\
i know you have to plot R against 1/A though, and pl is the gradient, and that was your question right?
woops my bad, that wasn't your question. well since you're varying A to get different values of R, then A is the independent variable and R is the dependent variable.
but could anyone tell me how exactly we're supposed to set this experiment up? i'm okay with the analysis and safety precautions and whatnot, just the actual experiment is like o.O

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