This thesis seeks to characterize the size of the interaction volume in a sample subject to electric force microscope (EFM) probing. It discusses the historical relevance of the EFM and the experimental method used. It then discusses the modeling of the fields surrounding the grating sample with the equivalent charge model (ECM) where a tip or other rotationally symmetric conducting element is replaced by a series of point charges on the vertical axis that mimic the original fields. The results of the model were then compared to the experimental data as well as a model simulated using COMSOL, a finite element analysis package. The electrostatic model was found to have good agreement with the simulated and experimental results and was then used to estimate the volume of interaction and the lateral resolution of this technique. The volume of interaction was estimated at 6000 μm3 and the lateral resolution was estimated at 10 μm.