I am a plant eco-physiologist working with leaf venation networks. I want to calculate the resistance of a vein segment in units of Ohms, using the formula Resistance = (resistivity * segment length)/ cross sectional area. I have the vein length in m, the vein cross-sectional area in cm2 and I calculated the vein resistivity using the Sack and Frole 2006 formula (DOI: 10.1890/05-0710) which gives the resistivity in units of MPa mmol-1 s m. How could I convert this resistivity in MPa mmol-1 s m to units of Ohm m (Ohms per meter)?

# Electronic – Resistivity unit conversions

resistanceresistivity

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## Best Answer

The Sack and Frole formula is for

hydraulicresistivity, which is related to fluidics, not electrical resistivity. They're different things so you can't convert.In basic SI units, electrical resistivity \$\rho\$ is in units of:

\$\text{kg}\cdot \text{m}^2\cdot A^{-2} \cdot s^{-2}\$ or in derived units \$\Omega\cdot \text{m}\$ or \$V\cdot A^{-1}\cdot \text{m}\$

The hydraulic resistivity is analogous in that the pressure (analogous to voltage) is in Pascals, the length in m and the flow rate (analogous to current flow in A = coulombs/s) in mmol/s but they are completely different physical things.