A Rod Is $4.0 \mathrm {~m}$ Long and Has a Square Cross-Section That Is

Multiple Choice

A rod is $4.0 \mathrm {~m}$ long and has a square cross-section that is $1.5 \mathrm {~cm}$ on each side. An ohmmeter measures $0.040 \Omega$ across its ends. What is the resistivity of the material from which this rod is made?

A) $0.015 \Omega \cdot \mathrm { m }$
B) $2.3 \times 10 ^ { - 6 } \Omega \cdot \mathrm { m }$
C) $0.023 \Omega \cdot \mathrm { m }$
D) $1.5 \times 10 ^ { - 4 } \Omega \cdot \mathrm { m }$