electric field (redirected from Electric force)

electric field

Region around an electric charge in which an electric force is exerted on another charge. The strength of an electric field E at any point is defined as the electric force F exerted per unit positive electric charge q at that point, or E = F/q. An electric field has both magnitude and direction and can be represented by lines of force, or field lines, that start on positive charges and terminate on negative charges. The electric field is stronger where the field lines are close together than where they are farther apart. The value of the electric field has dimensions of force per unit charge and is measured in units of newtons per coulomb.

---

electric field

a field of force surrounding a charged particle within which another charged particle experiences a force

---

Electric field

A condition in space in the vicinity of an electrically charged body such that the forces due to the charge are detectable. An electric field (or electrostatic field) exists in a region if an electric charge at rest in the region experiences a force of electrical origin. Since an electric charge experiences a force if it is in the vicinity of a charged body, there is an electric field surrounding any charged body.

The electric field intensity (or field strength) E at a point in an electric field has a magnitude given by the quotient obtained when the force acting on a test charge q^′ placed at that point is divided by the magnitude of the test charge q^′. Thus, it is force per unit charge. A test charge q^′ is one whose magnitude is small enough so it does not alter the field in which it is placed. The direction of E at the point is the direction of the force F on a positive test charge placed at the point. Thus, E is a vector point function, since it has a definite magnitude and direction at every point in the field, and its defining equation is Eq. (1).

(1) 

Electric flux density or electric displacement D in a dielectric (insulating) material is related to E by either of the equivalent equations shown as Eqs. (2),

(2) 

where P is the polarization of the medium, and ε is the permittivity of the dielectric which is related to ε ₀, by the equation ε = k ε ₀, k being the relative dielectric constant of the dielectric. In empty space, D = ε ₀ E .

In addition to electrostatic fields produced by separations of electric charges, an electric field is also produced by a changing magnetic field. See Electric charge, Electromagnetic induction, Potentials