A surface will be an equipotential surface if:
A. the electric charge density is constant everywhere on the surface.
B. the electric field is tangent to the surface at all points.
C. the electric charge density is zero everywhere on the surface.
D. the electric field is perpendicular to the surface at all points.
E. the net electric charge is zero on the surface.
Two point charges with charge +q are initially separated by a distance d. If you triple the charge on both charges, how far should the charges be separated for the potential energy between them to remain the same?
A. d/3
B. 3d
C. d/9
D. d
E. 9d
A spherical balloon made of rubber (an insulator) has a radius of 2.00 m. An amount of charge Q = -7.78E-6 C is uniformly distributed on the balloon. What is the electric field E at a point 2.40 m from the center of the balloon (in N/C; use a positive sign if E points away from the center and a negative sign if E points toward the center)?