NCCER Electrical Level Module 3 Study Questions and Correct Answers

Define Voltage? The driving force that makes current flow in a circuit. Voltage often represented by the letter E, is also referred to as electromotive force (emf), difference of potential, or electrical pressure. Define Current? The movement, or flow, of electrons in a circuit. Current(I) is measured in amperes. Define Resistance? An electrical property that opposes the flow of current through a circuit. Resistance (R) is measured in ohms. Define Watts? The unit of measurement for electrical power, represented by the letter W. Define Amperes? The basic unit of measurement for electrical current, represented by the letter A. What is a Coulomb? A unit of electrical charge equal to 6.25x10^18 electrons (or 6.25 quintillion electrons.) A coulomb is the common unit of quantity used for specifying the size of a given charge. What is an Ammeter? An instrument for measuring electrical current. What is an Ohmmeter? An instrument used for measuring resistance What is an Voltmeter? An instrument for measuring voltage. The resistance of the voltmeter is fixed. When the voltmeter is connected to a circuit, the current passing through the meter will be directly proportional to the voltage at the connection points. A Proton(+) repeals another? Proton(+) An Electron(-) repeals another? Electron(-) A Proton(+) attracts an? Electron(-) When no fourth band is present, the resistor tolerance is? + or - 20% In a parallel circuit, the total resistance is less than the? Smallest of the individual resistances. In-line ammeters are less common and must be? Connected in series with the circuit, which means that the circuit must be opened. What is a resistor? Any device in a circuit that resist the flow of electrons. Define Ohm's Law? A statement of the relationships among current, voltage, and resistance in an electrical circuit: current(I) equals voltage(E) divided by resistance(R). Generally expressed as a mathematical formula: I = E/R Define Watts law? P=(I)(E) or I=(P)/(E)