Two unknown wires, A and B

PHYSICS · Single correct · A Level · Physics · Electricity · Electricity

Problem

Two unknown wires, A and B, are characterized using current–voltage data. • For wire A, a graph of ΔV\Delta V versus II yields a straight line with slope 6 Ω6\,\Omega. • For wire B, a graph of II versus ΔV\Delta V yields a straight line with slope 0.10 A/V0.10\,\text{A/V}. Which statement correctly compares the resistances of the two wires? (a) Wire A has the greater resistance because RA=6 ΩR_A = 6\,\Omega while RB=0.10 ΩR_B = 0.10\,\Omega (slope of the II-versus-ΔV\Delta V graph taken directly as RBR_B) (b) Neither resistance can be determined without knowing the wires’ lengths and cross–sectional areas (confuses resistance with resistivity) (c) Wire B has the greater resistance because RB=10.10 A/VR_B = \frac{1}{0.10\,\text{A/V}} (d) Wire B has the greater resistance because RA=16 ΩR_A = \tfrac{1}{6}\,\Omega while RB=0.10 ΩR_B = 0.10\,\Omega (reciprocates only the wrong slope and mis-compares the numbers)

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