applied sciences Article Effect of Displacement Current on the Finite-Difference Modeling of Natural Source Electromagnetic Diffusion Yahui Xue 1,2,3, Jianxin Liu 1,2,3 , Rong Liu 1,2,3, Zhuo Liu 4, Rongwen Guo 1,2,3,* and Chuanghua Cao 5 1 School of Geosciences and Info-Physics, ...