A uniform wire has resistance . It is stretched evenly, without changing its volume, to times its original length. What is its new resistance, in ohms?
Answer and explanation
Correct answer: D. 4.5
- Step 1: State the resistance relation for a wire of resistivity , length , and cross-sectional area : .
- Step 2: Because volume is constant, stretching the length to decreases area to . Consequently, resistance scales as .
- Step 3: Calculate new resistance: .
Answer
4.5.
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