The characteristic of the electric field is to have a force on the charge, this force is the electric field force, positive charge force direction is the same as the direction of the electric field, negative charge force direction is opposite to the direction of the electric field.

The electric field is a substance, has energy, the field is strong where the electric field has a large energy.

Knowing the strength of the electric field can be determined by the force of the electric field on the charge, dielectric (insulator) electric breakdown is related to the size of the field strength.

The electric field strength of a point charge is determined by the point charge, independent of the test charge.

Formula for the field strength of a point charge in a vacuum: