Exam-style question
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Using the formula R = ρL/A, explain how the length and cross-sectional area of a wire affect its resistance.
Model answer
What a good answer should say
- According to the formula R = ρL/A, resistance (R) is directly proportional to the length (L) of the wire and inversely proportional to its cross-sectional area (A).
- This means that as the length of the wire increases, resistance increases, while increasing the cross-sectional area decreases resistance.
Explanation
Why this works
This question assesses the ability to apply the resistivity formula to explain the relationship between physical dimensions of a wire and its resistance. A strong answer demonstrates a clear understanding of how these factors interact, reinforcing the concept of resistivity in practical applications.
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