Write a note on specific conductivity $(k)$.

(N/A) The inverse of resistivity is called conductivity (specific conductance) and is represented by the symbol $k$ (Greek,kappa).
$k = \frac{1}{\rho}$
$IUPAC$ has recommended the use of the term conductivity over specific conductance.
The $SI$ units of conductivity are $S \ m^{-1}$,but quite often,$k$ is expressed in $S \ cm^{-1}$.
Conductivity of a material in $S \ m^{-1}$ is its conductance when it is $1 \ m$ long and its area of cross-section is $1 \ m^{2}$.
It may be noted that $1 \ S \ cm^{-1} = 100 \ S \ m^{-1}$.
Unit of kappa $(k): S \ m^{-1}$ or $S \ cm^{-1}$ or $\Omega^{-1} \ m^{-1}$ or $\Omega^{-1} \ cm^{-1}$.
Since $\rho = \frac{RA}{l}$,substituting this into $k = \frac{1}{\rho}$ gives:
$k = \left( \frac{l}{A} \right) \frac{1}{R}$
Since $G = \frac{1}{R}$ (conductance) and $G^{*} = \frac{l}{A}$ (cell constant):
$k = G \times G^{*}$