SAT Subject Physics Practice Question 208: Answer and Explanation

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Question: 208


The four wires are each made of aluminum. Which wire will have the greatest resistance?

A. Wire A
B. Wire B
C. Wire C
D. Wire D
E. All the wires have the same resistance because they’re all composed of the same material.

Correct Answer: B


The resistance of a wire made of a material with resistivity ρ and with length L and cross-sectional area A is given by the equation R = ρL/A. Since Wire B has the greatest length and smallest cross-sectional area, it has the greatest resistance.

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