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Chapter 20: Circuits and Circuit Elements Pictures found on http://physics.bu.edu/~duffy/PY106/Resistance.html Examples and table adapted from Physics textbook Section 1: Schematic Diagrams and Circuits


 * Schematic Diagram**: a graphic representation of an electric circuit, with standardized symbols representing circuit components.

** Schematic Diagram Symbols **:
 * **Component** || **Explanation** ||
 * Wire or conductor || * Wires that connect elements are conductors.
 * Because wires offer negligible resistance, they are represented by straight lines. ||
 * Resistor or circuit load || * Resistors are shown as wires with multiple bends, illustrating resistance to the movement of charges. ||
 * Bulb or lamp || * The multiple bends of the filament indicate that the light bulb is a resistor.
 * The symbol for the filament of the bulb is often enclosed in a circle to emphasize the enclosure of a resistor in a bulb. ||
 * Plug || * The plug symbol looks like a container for two prongs
 * The potential difference between the two prongs of a plug is symbolized by lines of unequal height. ||
 * Battery || * Differences in line height indicate a potential difference between positive and negative terminals of the battery.
 * The taller line represents the positive terminal of the battery. ||
 * Switch || * The small circles indicate the two places where the switch makes contact with the wires. Most switches work by breaking only one of the contacts, not both. ||
 * Capacitor || * The two parallel plates of a capacitor are symbolized by two parallel lines of equal height.
 * One curved line indicates that the capacitor can be used with only direct current sources with the polarity as shown. ||
 * Electric circuit**: a set of electrical components connected so that they provide one or more complete paths for the movement of charges


 * emf**: the energy per unit charge supplied by a source of electric current

Section 2: Resistors in series or in parallel


 * Series**: Describes a circuit or portion of a circuit that provides a single conducting path without junctions.
 * When many resistors are connected in series, the current (I) in each resistor is the same.
 * The total potential difference (V) is the sum of all the potential difference across the series circuit.
 * Equivalent resistance equals the total of individual resistances (R) in series.


 * Parallel**: Describes two or more components in a circuit that are connected across common points or junctions, providing separate conducting paths for the current
 * Resistors in parallel have the same potential difference (V) across them
 * The sum of currents (I) in parallel resistors equals the total current
 * The equivalent resistance (R) of resistors in parallel is calculated as the inverse of the equivalent resistance is equal to the sum of the inverse values of the component resistances.


 * Ohm's law**, V = I/R, can be used to find any unknowns in circuits.

Section 3: Complex Resistor Combinations

In everyday life, series and parallel circuits are combined in order to use the advantages of each type.

To find equivalent resistance, current, or potential difference in this circuit, you must use the relationships of both parallel and series circuits.

By grouping the series and parallel resistors, it is much easier to solve the problem.

If enough resistors are combined, there will only be a single resistor left to symbolize the equivalent resistance for the entire circuit.

To find the current or potential difference across a single resistor, you must first reduce the component resistors to their equivalent resistance. Then, calculate the current and potential difference across each group of resistors until the current and potential difference across the single resistor is known.