Conductance G = 1/R (Siemens). Conductivity kappa = G * $\frac{l}{A}$ = G * cell constant. Molar conductivity $Lambda_m$ = kappa * 1000/C (C in mol/L, giving units S.$cm^2$/mol). For strong electrolytes: $Lambda_m$ increases slightly with dilution and approaches Lambda_m_{infinity} linearly (Debye-Huckel-Onsager equation: $Lambda_m$ = Lambda_m_{infinity} - A*sqrt(C)). For weak electrolytes: $Lambda_m$ increases sharply at high dilution as dissociation increases. Lambda_m_{infinity} cannot be obtained by extrapolation for weak electrolytes — use Kohlrausch's law instead. Key: kappa decreases with dilution (fewer ions per unit volume), but $Lambda_m$ increases with dilution (more dissociation per mole of solute).