Electrical Potential Energy Chapter 18.1
Electrical Potential Energy • Electrical Potential Energy – Potential energy associated with an object due to its position relative to a source of electric force. • Similar to how the gravitational force associated with an object's position relative to earth creates gravitational potential energy.
Work in an Electric Field • A charged object can have potential energy by virtue of its location in an electric field. • Work is required to push a charged particle against the electric field of a charged body.
Uniform Electric Field • The electrical potential energy can be associated with a charge in a uniform field. • The electric potential energy will increase if the charge is negative and decrease if the charge is positive.
Electric Potential Energy in a Uniform Electric Field • This equation is only valid in a uniform electric field • Field lines are equally spaced apart in the entire electric field.
Electric Potential Pair of Charges • Electrical potential energy can be associated with a pair of charges. • Because the electric field is no longer uniform, a new equation must be used to describe the electric potential energy.
Electrical Potential Energy for a Pair of Charges • Positive work must be done to bring the charges together, so the electrical potential energy is positive for like charges and negative for unlike charges. • The expression can be used to determine the electrical potential energy for two or more charges.
Example Problem • In the classical model, an electron has a radius of r = 2.82x10-15m. Thus, two electrons could be as close as 2r. Calculate the electrical potential energy for two electrons that are touching.