Question

What is the unit of conductivity and resistivity respectively?

• A. Ohm, mho
• B. Mho, ohm
• C. Ohm m, mho/m
• D. Mho/m, ohm m

Answer 1

The correct option is D Mho/m, ohm m

Resistivity is given by $\rho =\frac{RA}{l}$
The units of $\rho$ will therefore be ohm m.
Since conductivity is
$\sigma =\frac{1}{\rho }$
Unit of conductivity is 1/(ohm m)
1/ohm has a special name – mho (I wonder who’s the genius that came up with that…)
So, unit of conductivity is mho/m.