What is the resistance of the wire and its uncertainty?

AI Thread Summary
The discussion revolves around calculating the resistance of a wire using Ohm's law, given a current of 1.0 ± 0.2 A and a potential difference of 8.0 ± 0.4 V. The calculated resistance is 8.0 ohms, but the uncertainty needs to be determined accurately. Participants note that the percentage uncertainties for current and voltage are 20% and 5%, respectively, leading to a total uncertainty of 25%. The conversation emphasizes the importance of including tolerance values in the calculations and suggests that the correct answer must reflect this uncertainty.
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Homework Statement


An experiment is done to measure the resistance of a wire.
The current in the wire is 1.0 \pm 0.2A and the potential difference across the wire is 8.0 \pm 0.4V.
What is the resistance of the wire and its uncertainty?

Homework Equations


-------------

The Attempt at a Solution



\frac{0.2}{1.0} \times 100 = 20\%

\frac{0.4}{8.0} \times 100 = 5\%

Total Percentage Uncertainty = 25\%

How can I get the uncertainty?
 
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looi76 said:

Homework Statement


An experiment is done to measure the resistance of a wire.
The current in the wire is 1.0 \pm 0.2A and the potential difference across the wire is 8.0 \pm 0.4V.
What is the resistance of the wire and its uncertainty?

Homework Equations


-------------

The Attempt at a Solution



\frac{0.2}{1.0} \times 100 = 20\%

\frac{0.4}{8.0} \times 100 = 5\%

Total Percentage Uncertainty = 25\%

How can I get the uncertainty?


Do you have a lab manual for your course? Sometimes they cover this in the introduction. Also, in this course, do they use calculus, or is it precalc?
 
I don't think this question need calculus! It is a multiple choice question and the choices are:
(A) (8.0 \pm 0.2)\omega
(B) (8.0 \pm 0.6)\omega
(C) (8 \pm 1)\omega
(D) (8 \pm 2)\omega
 
\omega?...I think You mean \Omega. You have been given the Voltage (V) and the Current (I). Use Ohm's law R = V/I to find the resistance. You can't add the percentages like that. Hint: You have to include the tolerance value of the Current and voltage in the formula.
 
looi76 said:
I don't think this question need calculus! It is a multiple choice question and the choices are:
(A) (8.0 \pm 0.2)\omega
(B) (8.0 \pm 0.6)\omega
(C) (8 \pm 1)\omega
(D) (8 \pm 2)\omega

Okay, which of those answers has a 25% uncertainty?
 

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