These branch wires eventually connect to each other to form a second node. Each light bulb is placed in its own separate branch. The branching location is referred to as a node. But this time, the connections of light bulbs is done in a manner such that there is a point on the circuit where the wires branch off from each other. Using the verbal description, one can acquire a mental picture of the circuit being described. But is this the only way that three light bulbs can be connected? Do they have to be connected in consecutive fashion as shown above? Absolutely not! In fact, example 2 below contains the same verbal description with the drawing and the schematic diagrams being drawn differently.Įxample 2: Description with Words: Three D-cells are placed in a battery pack to power a circuit containing three light bulbs. The path of a positive test charge leaving the positive terminal of the battery and traversing the external circuit would involve a passage through each one of the three connected light bulbs before returning to the negative terminal of the battery.
The above circuits presumed that the three light bulbs were connected in such a way that the charge flowing through the circuit would pass through each one of the three light bulbs in consecutive fashion. Straight lines have been used to connect the two terminals of the battery to the resistors and the resistors to each other. And note that each light bulb is represented by its own individual resistor symbol. Note that three sets of long and short parallel lines have been used to represent the battery pack with its three D-cells. Finally, the circuit symbols presented above can be used to represent the same circuit. This verbal description can then be represented by a drawing of three cells and three light bulbs connected by wires. Example 1: Description with Words: Three D-cells are placed in a battery pack to power a circuit containing three light bulbs. It will be important to either memorize these symbols or to refer to this short listing frequently until you become accustomed to their use.Īs an illustration of the use of electrical symbols in schematic diagrams, consider the following two examples. These circuit symbols will be frequently used throughout the remainder of Lesson 4 as electric circuits are represented by schematic diagrams. An open switch is generally represented by providing a break in a straight line by lifting a portion of the line upward at a diagonal. An electrical device that offers resistance to the flow of charge is generically referred to as a resistor and is represented by a zigzag line. A straight line is used to represent a connecting wire between any two components of the circuit. In both cases, the long line is representative of the positive terminal of the energy source and the short line represents the negative terminal. A collection of cells or battery is represented by a collection of long and short parallel lines. Some circuit symbols used in schematic diagrams are shown below.Ī single cell or other power source is represented by a long and a short parallel line. "A circuit contains a light bulb and a 1.5-Volt D-cell."Ī final means of describing an electric circuit is by use of conventional circuit symbols to provide a schematic diagram of the circuit and its components. Circuit drawings like the one below have been used many times in Lessons 1 through 3.
Such drawings provide a quicker mental picture of the actual circuit. But another means of describing a circuit is to simply draw it. Upon hearing (or reading) the words, a person grows accustomed to quickly picturing the circuit in their mind. On many occasions in Lessons 1 through 3, words have been used to describe simple circuits. Saying something like "A light bulb is connected to a D-cell" is a sufficient amount of words to describe a simple circuit. An electric circuit is commonly described with mere words. Former principles of electric potential difference, current and resistance will be applied to these complex circuits and the same mathematical formulas will be used to analyze them.Įlectric circuits, whether simple or complex, can be described in a variety of ways. Our discussion will progress from simple circuits to mildly complex circuits. Lesson 4 will focus on the means by which two or more electrical devices can be connected to form an electric circuit. Mathematical relationships between electrical quantities have been discussed and their use in solving problems has been modeled. Conceptual meaning of terms have been introduced and applied to simple circuits. Thus far, this unit of The Physics Classroom tutorial has focused on the key ingredients of an electric circuit and upon the concepts of electric potential difference, current and resistance.
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