In these first two lessons of the Circuits unit of The Physics Classroom, an effort has been made to present a model of how and why electric charge flows within an electric circuit. Terms have been defined and rules and principles presented and discussed. The goal has been to help students of physics to construct an…
Electric circuits are designed to serve a useful function. The mere movement of charge from terminal toterminal is of little use if the electrical energy possessed by the charge is not transformed into another useful form. To equip a circuit with a battery and a wire leading from positive to negative terminal without an electrical device (light…
Suppose that you were given a small light bulb, an electrochemical cell and a bare copper wire and were asked to find the four different arrangements of the three items that would result in the formation of an electric circuit that would light the bulb. What four arrangements would result in the successful lighting of…
What is an Electric Circuit? In Lesson 1, the concept of electric potential difference was discussed. Electric potential is the amount of electric potential energy per unit of charge that would be possessed by a charged object if placed within an electric field at a given location. The concept of potential is a location-dependent quantity – it…
In the previous section of Lesson 1, the concept of electric potential was introduced. Electric potential is a location-dependent quantity that expresses the amount of potential energy per unit of charge at a specified location. When a Coulomb of charge (or any given amount of charge) possesses a relatively large quantity of potential energy at a…
In the previous section of Lesson 1, it was reasoned that the movement of a positive test charge within an electric field is accompanied by changes in potential energy. A gravitational analogy was relied upon to explain the reasoning behind the relationship between location and potential energy. Moving a positive test charge against the direction of…
Electric Potential Difference Electric Field and the Movement of Charge Perhaps one of the most useful yet taken-for-granted accomplishments of the recent centuries is the development of electric circuits. The flow of charge through wires allows us to cook our food, light our homes, air-condition our work and living space, entertain us with movies and…
most known and powerful display of electrostatics in nature is a lightning storm. Lightning storms are inescapable from humankind’s attention. They are never invited, never planned and never gone unnoticed. The rage of a lightning strike will wake a person in the middle of the night. They send children rushing into parent’s bedrooms, crying for assurance…
We have previously shown in Lesson 4 that any charged object – positive or negative, conductor or insulator – creates an electric field that permeates the space surrounding it. In the case of conductors there are a variety of unusual characteristics about which we could elaborate. Recall from Lesson 1 that a conductor is material that allows…
In the previous section of Lesson 4, the vector nature of the electric field strength was discussed. The magnitude or strength of an electric field in the space surrounding a source charge is related directly to the quantity of charge on the source charge and inversely to the distance from the source charge. The direction of the electric…