Electric Potential - Electricity and Optics - Lecture Slides, Slides of Electrical Engineering

Download Electric Potential - Electricity and Optics - Lecture Slides and more Slides Electrical Engineering in PDF only on Docsity! 1/25/12 1 Lectures 6 & 7: Chapter 23 1/25/12 1 Electric Potential q A C B r A B r Path independence Equipotential surfaces R R R r V Q 4pe0 r Q 4pe0 R 1/25/12 2 From Mechanics (PHYS 152/172) •  Energy •  Conservative Forces: Kinetic Energy: associated with the state of motion Potential Energy: associated with the configuration of the system Work done by a conservative force is independent of path 1/25/12 3 From Mechanics (PHYS 152/172) •  Work 1/25/12 4 Electric Potential Energy When an electrostatic force acts between two or more charges within a system, we can assign an Electric Potential Energy: F x Coulomb force does negative work Potential energy increases + + + + 1/25/12 2 1/25/12 5 Example: Electric Potential Energy What is the change in electrical potential energy of a released electron in the atmosphere when the electrostatic force from the near Earth’s electric field (directed downward) causes the electron to move vertically upwards through a distance d? 1.  U of the electron is related to the work done on it by the electric field: 2.  Work done by a constant force on a particle undergoing displacement: 3.  Electrostatic Force and Electric Field are related: 1/25/12 6 Electric Potential The potential energy per unit charge has a unique value at any point in an electric field. 1/25/12 7 Potential Difference The potential difference between two points is the negative of the work done by the electrostatic force to move a unit charge from one point to another. 1/25/12 8 Electric Potential versus Electrical Potential Energy Electric Potential is a property of an electric field and is measured in J/C or V Electric Potential Energy is an energy of system consisting of the charged object and the external electric field, and is measured in Joules.