To derive the electric field at a point charge q, the voltage V is expressed as V = kq/r, where k is Coulomb's constant and r is the distance from the charge. The electric field components can be calculated using E(x) = V/x, E(y) = V/y, and E(z) = V/z, leading to a general expression for the electric field E(r). However, at the exact location of the point charge, the electric field becomes undefined in classical electrodynamics due to singularity. Quantum effects may need to be considered for a complete understanding. The discussion emphasizes the limitations of classical models in describing electric fields at point charges.
