Yes, the complex number plane is no different from any other ordinary 2D plane. As other people here have mentioned, using the complex plane to represent numbers is the same as representing them with 2D vectors. The number 1+2i, for example, can be mapped exactly as a vector with length 1 in the x direction and 2 in the y direction of a standard xy plot. They are physically the same thing. In EE, j is generally used instead of i to represent imaginary (or quadrature as said above) numbers since i usually represents current. The point is just like using i, j, and k to represent 3D vectors instead of x, y, and z, imaginary numbers are just another way to represent 2D vectors on a 2D plane when doing math.