# What is the resistance of the wire and its uncertainty?

• looi76
In summary, an experiment was conducted to measure the resistance of a wire by calculating the percentage uncertainties of the current and potential difference. The total percentage uncertainty was found to be 25%. The resistance of the wire can be determined using Ohm's law, and the choices for the uncertainty of the resistance are (A) (8.0 \pm 0.2)\Omega, (B) (8.0 \pm 0.6)\Omega, (C) (8 \pm 1)\Omega, and (D) (8 \pm 2)\Omega.

## 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?

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## 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?

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?

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

## 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?