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What is the resistance of the wire and its uncertainty?

  • Thread starter looi76
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  • #1
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Homework Statement


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

Homework Equations


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

The Attempt at a Solution



[tex]\frac{0.2}{1.0} \times 100 = 20\%[/tex]

[tex]\frac{0.4}{8.0} \times 100 = 5\%[/tex]

Total Percentage Uncertainty = [tex]25\%[/tex]

How can I get the uncertainty?
 

Answers and Replies

  • #2
seycyrus

Homework Statement


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

Homework Equations


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

The Attempt at a Solution



[tex]\frac{0.2}{1.0} \times 100 = 20\%[/tex]

[tex]\frac{0.4}{8.0} \times 100 = 5\%[/tex]

Total Percentage Uncertainty = [tex]25\%[/tex]

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?
 
  • #3
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I don't think this question need calculus! It is a multiple choice question and the choices are:
(A) [tex](8.0 \pm 0.2)\omega[/tex]
(B) [tex](8.0 \pm 0.6)\omega[/tex]
(C) [tex](8 \pm 1)\omega[/tex]
(D) [tex](8 \pm 2)\omega[/tex]
 
  • #4
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4
[itex]\omega[/itex]?...I think You mean [itex]\Omega[/itex]. 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.
 
  • #5
Redbelly98
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I don't think this question need calculus! It is a multiple choice question and the choices are:
(A) [tex](8.0 \pm 0.2)\omega[/tex]
(B) [tex](8.0 \pm 0.6)\omega[/tex]
(C) [tex](8 \pm 1)\omega[/tex]
(D) [tex](8 \pm 2)\omega[/tex]
Okay, which of those answers has a 25% uncertainty?
 

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