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Physics paper 5 notes?

afoo.666

afoo.666

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Error bars are drawn only on those points which are passing through best fit line?
 
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sagar65265

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kiara15 said:
http://papers.xtremepapers.com/CIE/...nd AS Level/Physics (9702)/9702_w11_qp_52.pdf
gradient of WA line greater than best fit line , and according to formula negative uncertainity is coming. how to determine uncertaintiy in such cases?????
Click to expand...

If i've understood your question correctly (sorry if I haven't - please correct me in that case!), then the matter should be easy to resolve:

The gradient of the Worst Acceptable Line can be a little more than or a little less than the gradient of the Best Fit Line (If you join the top of the first error bar to the bottom of the last error bar, then the gradient of the WAL will be less than that of the Best Fit Line, but if you join the bottom of the first error bar to the top of the last error bar, then the gradient of the WAL will be more than that of the Best Fit Line).

So if your value for the uncertainty is coming to be negative when you subtract one gradient from the other, it just means that the WAL you've drawn is the line with gradient:

Best Fit Line gradient + Uncertainty

rather than the line with gradient

Best Fit Line - Uncertainty.

Since the error bars are of equal length on either side of the plotted point, the gradient of the other WAL will be equal to the Gradient of the BFL - Uncertainty.

So just take the modulus of the uncertainty you're getting, or just add +/- to it, because you've gotten the - value, the same uncertainty should apply to the + uncertainty value.

Hope this helped!

Good Luck for all your exams!
 
kiara15

kiara15

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sagar65265 said:
If i've understood your question correctly (sorry if I haven't - please correct me in that case!), then the matter should be easy to resolve:

The gradient of the Worst Acceptable Line can be a little more than or a little less than the gradient of the Best Fit Line (If you join the top of the first error bar to the bottom of the last error bar, then the gradient of the WAL will be less than that of the Best Fit Line, but if you join the bottom of the first error bar to the top of the last error bar, then the gradient of the WAL will be more than that of the Best Fit Line).

So if your value for the uncertainty is coming to be negative when you subtract one gradient from the other, it just means that the WAL you've drawn is the line with gradient:

Best Fit Line gradient + Uncertainty

rather than the line with gradient

Best Fit Line - Uncertainty.

Since the error bars are of equal length on either side of the plotted point, the gradient of the other WAL will be equal to the Gradient of the BFL - Uncertainty.

So just take the modulus of the uncertainty you're getting, or just add +/- to it, because you've gotten the - value, the same uncertainty should apply to the + uncertainty value.

Hope this helped!

Good Luck for all your exams!
Click to expand...

oh ok, for examp in oct/nov/11/p52 neg uncertainity is coming i.e -0.06 so after taking mod itwil be 0.06?
p.s thaaanks for explanation which i partially understoodo_O:sneaky:
 
kiara15

kiara15

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ohh ok. we wil values of best fit and worst fit?
fb.junks said:
U need to calculate N by using the gradient.First with best fit and the worst acceptable line gradient.Then the N of best fit-N of worst acceptable.I think u will get the uncertainty.
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,
 
insipid_life

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Hey Can anybody tell me what gradient did you get? for paper 5 of oct/nov 2009 variant 52
 
kitty_toxic

kitty_toxic

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wait o
Asel Panduwawala said:
Log AUC= (Log of Maximum-Log on Minimum)/2
Eg: IF the say X=500+-5
then auc= ((log505)-(log495))/2

PS- I usually keep the value to the same number of sf as the raw data that i used to calculate it. And the error to 1 sf below the raw data. (be careful if you have 1 sf i raw data then keep both the calculated value and error to 1 sf) Usually the error is left to 1sf but the marking schemes allow more sf.

Hope this is helpful and sorry for the late reply guys.

Proudly to be Lankan lion
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wait i dont get it, why divide by 2?????? for ex: in oct/nov 2011 for lgT it was simple log28-log24, to give o.07, so the rule u stated, what situation is it for???
 
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sagar65265

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waver525 said:
does any one know how to draw a photocell .... it is asked in may 2011 51 ??
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Hopefully the following website will help:

http://symbols.radicasoftware.com/Symbol/Single/PC/Photo-Cell.html

However, I doubt that the exact circuit symbol for the photocell would be required in the diagram, since it doesn't say anywhere that the symbol is required, as far as I've seen, and it only says that a labelled diagram is enough. In its own words,

"Labelled diagram of apparatus: lamp, glass sheet and photocell in line."

So i'm guessing that just labelling a block or something as a photocell might be enough; although, if you want to stay on the safe side and use the symbol anyways, its there on the link above.

Good Luck for all your exams!
 
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