Final answer:
The electric field at the surface of a charged conductor is directly proportional to the surface charge density as per electrostatic equilibrium and Gauss's Law.
Step-by-step explanation:
The electric field at the surface of a charged conductor is indeed directly related to the surface charge density. This is due to the nature of electrostatic equilibrium, where the electric field inside the conductor is zero and any excess charge resides on its surface. Therefore, since electric field lines are perpendicular to the surface, the electric field strength is proportional to the surface charge density, often denoted as σ (sigma). This principle is derived from Gauss's Law which relates the electric flux through a closed surface to the charge enclosed by that surface. The relationship can be expressed as E = σ/ε, where ε is the permittivity of the medium surrounding the conductor, confirming the direct proportionality between electric field and surface charge density.