{"knowledge_schema": {"broad_category": "Physics \u2192 Electrostatics \u2192 Electric Fields", "refinement": "This problem involves understanding the behavior of electric fields around conductors and the effects of charges placed within cavities.", "specific_scope": "The focus is on a neutral spherical conductor with a cavity containing a negative charge, and determining the electric field at a point outside the conductor.", "goal": "Calculate the electric field at a point outside the conductor, considering the influence of the charge inside the cavity and the properties of conductors."}, "summary": "In this problem, we analyze the electric field produced by a neutral spherical conductor with a cavity containing a negative charge. The key principle is that the electric field outside a conductor is determined solely by the net charge enclosed within it. Since the conductor is neutral and the negative charge -q induces a positive charge +q on the inner surface of the conductor, the outer surface remains neutral. Therefore, at a point outside the conductor, the electric field behaves as if the charge -q were located at the center of the conductor, leading to the conclusion that the electric field at a distance L from the center is given by E = q/4 \u03c0\u03f5_0 L^2."}