The SI unit of resistivity is
Correct answer: B. ohm metre
- A. ohm
- B. ohm metre
- C. ohm per metre
- D. volt per ampere
Explanation
Rearranging R equals rho L over A gives rho equal to RA over L, whose units are ohm times metre squared divided by metre, that is ohm metre. The plain ohm, equivalently the volt per ampere, is the unit of resistance itself. Resistivity is a material property, so copper has the same resistivity whether it is a thin wire or a thick bar.
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About Resistance and Resistivity
Resistance measures opposition to current in a conductor and follows R = V/I for an ohmic conductor, while resistivity is an intrinsic property of the material. Questions use R = ρL/A, examine effects of length, cross-sectional area and temperature, and distinguish resistance, resistivity, conductance and conductivity.
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