Electric Potential Energy and Electric Potential

Electric Potential Energy and Electric Potential

1. Electric Force as a Conservative Force

   • When a force is conservative then the work depends only on the initial and final positions.
     • A conservative electric force is then, when the work done by the electric force is the same when a charge changes position (from A to B) regardless of the path taken.
       • Concept of Electric Potential Energy
         • a potential energy can be associated to any system in which a particle is located within an electric field and receives the action of an electrostatic force.
           • This means that when a particle with a positive or negative charge moves within an electric field, it will exert an attractive or repulsive force that performs a work over the particle.
             • Electric potential energy of a system of fixed point charges, according to Resnick, Halliday & Krane (1999), is equal to the work that an external agent must perform to make up the system, bringing each charge from an infinite distance.
               • The electric potential is also called just potential and it is the electric potential energy per unit charge. In other words, the electric potential will tell us how much electric potential energy one coulomb will have if placed in a specific location.

2. Electric Potential of a Point Charge and of a System of Point Charges

   • Sears & Zemansky (2013) state that the electric potential at a certain point is the electric potential associated to a unit charge placed at that point
     • “The potential difference between two points is the work per unit positive charge that electric forces perform to move a small test charge from a point of higher potential to a point of lower potential”
       • Energy Conservation with Electric Force
         • According to the conservation of energy law, energy can be neither created nor destroyed.
           • Potential energy can be produced by the work applied by the gravity over an object or by the stored energy on a spring, but it can also be the result of the storage of electric potential energy.
             • The potential difference between the two plates with opposite charges is equal to the product of the field intensity and the separation between the plates.
               • “The magnitude <<e>> of the electron charge is used to define an energy unit that is useful in many calculations with atomic and nuclear systems”