静电场中某点P处电势的数值等于___ The value of the potential at some point P in the electrostatic field is equal to___
A、试验电荷q0置于P点时具有的电势能; the potential energy of the test charge q0 at point P;
B、单位试验电荷置于P点时具有的电势能; the electric potential energy of the unit test charge at point P;
C、单位正电荷置于P点时具有的电势能; the electric potential energy of a unit positive charge at point P;
D、把单位正电荷从P点移到电势零点时外力所作的功; the work done by the external force when the unit positive charge is moved from P to zero of the electric potential;