Standard Cell Potential Significant Figures on Midterm

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Ranger Saldivar 2D
Posts: 28
Joined: Fri Sep 25, 2015 3:00 am

Standard Cell Potential Significant Figures on Midterm

Postby Ranger Saldivar 2D » Sat Feb 20, 2016 1:55 pm

For the recent midterm on question 8 why is there three siginificant answers in the form of 1.20V when the two other cell standard cell potentials of .80V and -.40V only have 2 significant figures?

Bryan Lau 3H
Posts: 53
Joined: Fri Sep 25, 2015 3:00 am

Re: Standard Cell Potential Significant Figures on Midterm

Postby Bryan Lau 3H » Sat Feb 20, 2016 3:38 pm

Because for addition the rules for sig figs are different. You round with respect to the number whose digits place ends furthest to the left. For example, .80 and .40 are both to the hundredths place, so the answer upon addition will be rounded to the hundredths place.

Therefore, the answer is 1.20 and not 1.2

BrandonV
Posts: 6
Joined: Wed Nov 18, 2015 3:00 am

Re: Standard Cell Potential Significant Figures on Midterm

Postby BrandonV » Sat Feb 20, 2016 10:32 pm

Because .80V and .40V is the same as 0.80V and 0.40V, which is 3 significant figures

Bryan Lau 3H
Posts: 53
Joined: Fri Sep 25, 2015 3:00 am

Re: Standard Cell Potential Significant Figures on Midterm

Postby Bryan Lau 3H » Fri Feb 26, 2016 12:38 pm

BrandonV wrote:Because .80V and .40V is the same as 0.80V and 0.40V, which is 3 significant figures


Actually, I don't think you should consider the sig figs like this. 0.80V and 0.40V are still 2 sig figs. Rather, you should treat the sig figs like how I mentioned in the previous comment. Rules for sig figs are different when dealing with addition/subtraction, compared to when dealing with multiplication/division.


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