18-4-electric-potential_summary

Section 18.4 Electric Potential discusses the concept of electric potential energy and its relationship with electric potential. The learning objectives help students understand the differences and similarities between electric potential energy and gravitational potential energy, calculate the electric potential difference between two point charges and in a uniform electric field, and apply the concepts of potential in real-life situations. The key terms introduced in this section are potential energy, electric potential, and potential difference. Potential energy is the energy stored in an object due to its position with respect to another object. Potential is used in everyday life to describe a situation where an object has the potential to do work. Gravitational potential energy is the potential energy related to the gravitational field, while electric potential energy is the potential energy related to the electric field. In this section, the analogy between gravitational potential energy and electric potential energy is presented. The gravitational potential energy of a mass increases when it is raised in a gravitational field, while the electric potential energy of a charge increases when it is moved farther from another charged object. The potential energy of a system decreases when an object is moved closer to another object, while the potential energy increases when an object is moved farther away. The electric potential difference (voltage) between two points in a uniform electric field is calculated using the equation V = Ed, where V is the voltage, E is the electric field, and d is the distance between the two points. In a constant electric field, the potential difference is directly proportional to the electric field and the distance between the two points. The electric field can also be calculated from the potential difference using the equation E = V/d. In cases where the electric field is not uniform, the calculation of electric potential energy becomes more complex. For example, for two point charges of the same sign, the electric potential energy decreases as the charges get closer, while for charges of opposite signs, the electric potential energy increases as the charges get closer. Finally, the section discusses the analogy between electric potential and pressure in fluids. Just as pressure pushes fluid from regions of high pressure to regions of low pressure, an electric potential difference pushes positive charges from regions of high potential to regions of low potential. The section provides an analogy between gravity and electricity, drawing parallels between gravitational potential energy and electric potential energy. It explains how electric potential energy can be used to calculate the motion of charges in an electric field and how the electric potential difference is analogous to pressure in fluids. The key equations and concepts are presented, along with worked examples, practice problems, and grasp checks to reinforce understanding. The section also discusses the use of electric potential in various fields, including the behavior of electric fish and the operation of X-ray tubes.