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

## 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?

seycyrus

## 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.

Redbelly98
Staff Emeritus
Science Advisor
Homework Helper
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?