To move the positive charge of - 8 power Coulomb with charge quantity of 1 * 10 from infinite distance to point a in the electric field, we need to overcome the electric field force to do work w = 1.2 * 10-4 power Joule,

To move the positive charge of - 8 power Coulomb with charge quantity of 1 * 10 from infinite distance to point a in the electric field, we need to overcome the electric field force to do work w = 1.2 * 10-4 power Joule,

The positive work of electric field force is equal to the decrease of electric potential energy, and the negative work of electric field force is equal to the increase of electric potential energy
W = 0-epa
EPA = - W electricity = w = 1.2 * 10-4 power Joule
The potential of this point = w / Q = 1.2 * 10-4 / 1 * 10-8 = 1.2 * 10 ^ 4V

Coulomb's constant k of electrostatic force is measured by experiment, and Coulomb's law is put forward
What's wrong

Coulomb's law is first put forward through experiments, and then the electrostatic constant k is measured through experiments
Pay attention to the order of time

When a positive point charge with q = 2 × 10-6c is moved from a point outside the electric field (zero potential) to a point in the electric field, and the work done by the electric field force is 4 × 10-5j, the potential of point a is 0______ ．

The potential of a and zero potential point is: φ a = ua0 = wa0q = − 4 × 10 − 52 × 10 − 6 = - 20V, so the answer is: - 20V