Exam-style question
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Describe how the cross-sectional area of a wire influences its resistance, using a relevant formula.
Model answer
What a good answer should say
- The resistance of a wire decreases as its cross-sectional area increases.
- This relationship is expressed in the formula R = ρ(L/A).
- In this formula, R is resistance, ρ is resistivity, L is the length of the wire, and A is the cross-sectional area.
- A larger cross-sectional area (A) results in a smaller resistance (R), assuming length and resistivity are constant.
Explanation
Why this works
This answer is strong because it clearly explains the inverse relationship between cross-sectional area and resistance, supported by the relevant formula. It tests the understanding of how the physical characteristics of a conductor affect its resistance, which is essential in the study of electricity.
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