Physics

Problem

Two unknown wires, A and B, are characterized using current–voltage data. • For wire A, a graph of

\Delta V

versus

I

yields a straight line with slope

6\,\Omega

. • For wire B, a graph of

I

versus

\Delta V

yields a straight line with slope

0.10\,\text{A/V}

. Which statement correctly compares the resistances of the two wires? a) Wire A has the greater resistance because

R_A = 6\,\Omega

while

R_B = 0.10\,\Omega

(slope of the

I

-versus-

\Delta V

graph taken directly as

R_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

R_B = \frac{1}{0.10\,\text{A/V}}

d) Wire B has the greater resistance because

R_A = \tfrac{1}{6}\,\Omega

while

R_B = 0.10\,\Omega

(reciprocates only the wrong slope and mis-compares the numbers)

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