Exam-style question
Try this first
A copper wire has a length of 2.0 m and a cross-sectional area of 1.0 mm². If the resistivity of copper is 1.68 x 10^-8 Ωm, calculate the resistance of the wire. Scenario focus: a wire-diameter comparison, where the answer must focus on cross-sectional area rather than circuit current.
Model answer
What a good answer should say
- The resistance of the wire is 0.0336 Ω.
Explanation
Why this works
The correct answer is The resistance of the wire is 0.0336 Ω.. In this version, the deciding idea is a wire-diameter comparison, where the answer must focus on cross-sectional area rather than circuit current.
That makes the correct option the one that uses the appropriate electricity quantity and unit, while the distractors either swap related circuit quantities or apply a rule from the wrong circuit situation.
Common mistake
No common mistake is linked to this question yet.