Final answer:
The electric field strength just above one face of a copper penny in isolation would be zero, because isolated conductors in equilibrium cannot sustain an electric field on their surface.
Step-by-step explanation:
The electric field strength just above one face of a copper penny would be essentially zero if the penny is isolated and not near any other charged object or external electric field. This is because an isolated conducting object in equilibrium can't sustain an electric field inside or on its surface since the charges redistribute themselves to cancel any existing field within the conductor. To determine an electric field strength above the surface of a charged conductor or between two charged plates, one simple formula is E = V/d, where E is the electric field strength, V is the potential difference, and d is the separation between the plates.