Potential Difference

Basic Electrical Theory ATOM AND ITS FORCES The strength of the attraction or of the repulsion force depends upon two factors: (1) the amount of charge on each object, and (2) the distance between the objects. The greater the charge on the objects, the greater the electrostatic field. The greater the distance between the objects, the weaker the electrostatic field between them, and vice versa. This leads us to the law of electrostatic attraction, commonly referred to as Coulomb’s Law of electrostatic charges, which states that the force of electrostatic attraction, or repulsion, is directly proportional to the product of the two charges and inversely proportional to the square of the distance between them as shown in Equation 1-1. (1-1) F K q₁ q₂ d² where F = force of electrostatic attraction or prepulsion (Newtons) K = constant of proportionality (Coulomb²/N-m²) q₁ = charge of first particle (Coulombs) q₂ = charge of second particle (Coulombs) d = distance between two particles (Meters) If q₁ and q₂ are both either Figure 7 Potential Difference Between Two Charged Objects positively or negatively charged, the force is repulsive. If q₁ and q₂ are opposite polarity or charge, the force is attractive. Potential Difference Potential difference is the term used to describe how large the electrostatic force is between two charged objects. If a charged body is placed between two objects with a potential difference, the charged body will try to move in one direction, depending upon the polarity of the object. If an electron is placed between a negatively-charged body and a positively-charged body, the action due to the potential difference is to push the electron toward the positively-charged object. The electron, being negatively charged, will be repelled from the negatively-charged object and attracted by the positively-charged object, as shown in Figure 7. Rev. 0 Page 5 ES-01