Exam-style question
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If a wire has a resistivity of 2.5 x 10^-6 Ω·m and a length of 3 m, what is the resistance if the cross-sectional area is 1 mm²? Scenario focus: a material-choice question, where resistivity is used to compare conductors independently of their shape.
- A.0.0075 Ω
- B.0.075 Ω
- C.0.025 Ω
- D.0.25 Ω
Model answer
What a good answer should say
- 0.075 Ω
Explanation
Why this works
The correct answer is 0.075 Ω. In this version, the deciding idea is a material-choice question, where resistivity is used to compare conductors independently of their shape.
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.