Electric field just outside a charged conductor is perpendicular to the surface.

Electric field just outside a charged conductor is perpendicular to the surface.

• A. True
• B. False
• C. Sometimes parallel
• D. The field is always zero

Answer: (B)

Electric fields at a conductor’s surface follow a clear boundary condition in electrostatics. Inside a conductor in static equilibrium, the field is zero and the surface becomes an equipotential. Free charges on the surface rearrange themselves so that there is no tangential electric field along the surface; any tangential component would push charges to move until it disappears. As a result, the field just outside the conductor has no tangential component and is directed normal (perpendicular) to the surface. The normal component of the field just outside equals sigma/epsilon0, where sigma is the surface charge density, while the field inside remains zero. So the field immediately outside a charged conductor is perpendicular to the surface. This holds for static situations; time-varying or non-equilibrium scenarios can alter the situation, but in the usual electrostatics context the statement is true.

Electric fields at a conductor’s surface follow a clear boundary condition in electrostatics. Inside a conductor in static equilibrium, the field is zero and the surface becomes an equipotential. Free charges on the surface rearrange themselves so that there is no tangential electric field along the surface; any tangential component would push charges to move until it disappears. As a result, the field just outside the conductor has no tangential component and is directed normal (perpendicular) to the surface. The normal component of the field just outside equals sigma/epsilon0, where sigma is the surface charge density, while the field inside remains zero. So the field immediately outside a charged conductor is perpendicular to the surface. This holds for static situations; time-varying or non-equilibrium scenarios can alter the situation, but in the usual electrostatics context the statement is true.