Abstract
This study analyzes the variation in electrical resistivity in commercial 2B grade graphite cores as a function of relative humidity (RH). The electrical resistivity of 2B and HB grade graphite cores was also analyzed according to their clay content. Experimental measurements obtained in the coastal environment of Lima, with a relative humidity of 75\%, were compared to those taken in an artificially dehumidified environment at 49\% RH. Using electrical resistance measurements performed with a multimeter and applying Pouillet's Law, the electrical resistivity values for the analyzed samples were determined. For the 2B grade graphite mine, values of $2.41\times10^{-4}$ $\Omega\cdot\text{m}$ were obtained at 75\% RH and $2.78\times10^{-4}$ $\Omega\cdot\text{m}$ at 49\% RH, showing an approximate variation of 15.4\% in electrical resistivity. The results show that electrical resistivity decreases under conditions of higher relative humidity, an effect associated with the porous and hygroscopic nature of the binding clay, which promotes the adsorption of water molecules and modifies electron transport. Furthermore, it was observed that HB graphite cores with a higher clay content exhibit lower electrical resistivity value compared to 2B graphite cores. These findings suggest that commercially available graphite cores could be used as low-cost materials with potential applications in the development of sensors for monitoring ambient humidity.