2.2 The electric field intensity e Definition: the electric field intensity due to the point charge Qa is ab Q2 ar. Qb4m∈0r Explanation (1)it's the force exerted on a unit test charge; (2)E has a unit volt/meter (3)Ea is a vector field over the whole space; (4 )Ea exists as long as Qa is present, regardless of Qb(important) (5)It' very simple to get the force acting on Q F=QE