# Electrical Sciences DC Theory

 Two or more chemical cells connected in a series. Batteries Graphic representation used to show the relationship between component group or stages in a circuit. Block diagram Direction of electron flow is from a point of negative potential to a point of positive potential. Conventional and electron flow To find the individual branch currents in a parallel circuit when only resistance and total current are known, the resistance in each circuit can be used to divide the total current into fractional currents in each branch. Current division Sum of the currents flowing through each branch of a parallel circuit is equal to the total current flow in the circuit. Current in parallel An armature coil cuts across the magnetic field to produce a voltage output. DC generator When the positive terminal of a voltage source is connected to a diode’s anode, and the negative terminal is connected to the cathode. Forward bias A circuit that rectifies the entire cycle of the AC sine wave. Full-wave rectifier When a single diode is used in a rectifier circuit, current will flow through the circuit only during one half of the input voltage cycle. Half-wave rectifier Law 1: The sum of the voltage drops around a closed loop is equal to the sum of the voltage sources of that loop (Kirchhoff’s Voltage Law). Law 2: The current arriving at any junction point in a circuit is equal to the current leaving that junction (Kirchhof’'s Current Law). Kirchhoff’s laws Graphic representation showing the components of a circuit by means of single lines and the appropriate graphic symbols. One-line diagram If one of the paths for current to flow is opened, current will continue to follow as long a some or more of the remaining paths provides a complete path. Open circuit (parallel) If the path for current is broken no current flows. Open circuit (series) Circuits that have two or more components connected across the same voltage source. Parallel circuit Converts AC power to DC power. Rectifiers Total resistance in a parallel circuit can be found by applying Ohm’s Law. Divide the voltage across the parallel resistance by the total line current. Resistance in parallel Total resistance in a series circuit is equal to the sum of all the parts of that circuit. Resistance in series The measure of the resistance a material imposes on current flow. Resistivity When the diode’s anode is connected to the negative side of the source, and the cathode is connected to the positive side of the source. Reverse bias The standard means by which we communicate information in electrical and electronics circuits. Schematic diagram A circuit where there is only one path for current flow. Series circuit A sudden and very large increase in circuit current associated with a zero or very low resistance current path. Short circuit (parallel) If there is no resistance in a circuit or if resistance suddenly becomes or approaches zero, a very large current will flow. Condition of very low resistance and high current flow. Short circuit (series) Is defined as the amount of change of the resistance of a material for a given change in temperature. Temperature coefficient (α) Consists of two different types of metal joined at a junction and is used to convert heat energy into a voltage output. Thermocouples Used when it is necessary to obtain different values of voltage from a single energy source. Voltage divider A very simple way to show wiring connections in an easy to follow manner. Wiring diagram LIST the four ways to produce a DC voltage. BatteriesDC GeneratorThermocouplesRectifiers STATE the purpose of a rectifier. The purpose of a rectifier circuit is to convert AC power to DC power DESCRIBE the outputs of the following circuits: a. Half-wave rectifier b. Full-wave bridge rectifier When a single diode is used in a rectifier circuit, current will flow through the circuit only during one-half of the input voltage cycle A full-wave rectifier circuit is a circuit that rectifies the entire cycle of the AC sine-wave DESCRIBE what is meant by the term “voltage divider”. A voltage divider, or network, is used when it is necessary to obtain different values of voltage from a single energy source DESCRIBE the voltage and current effects of an open in a series DC circuit Circuits can be opened deliberately, such as by the use of a switch, or they may be opened by a defect, such as a broken wire or a burned-out resistor. Since no current flows in an open series circuit, there are no voltage drops across the loads. The loads consume no power, and total power consumed by the circuit is zero. DESCRIBE the voltage and current effects in a shorted DC circuit. If there is no resistance in a circuit, or if the resistance suddenly becomes or approaches zero, a very large current will flow. STATE Kirchhoff’s Voltage Law The sum of the voltage drops around a closed loop is equal to the sum of the voltage sources of that loop STATE Kirchhoff’s Current Law. The current arriving at any junction point in a circuit is equal to the current leaving that junction Block Diagram One Line Wiring Diagram Schematic Diagram The measure of the resistance a material imposes on current flow. Resistivity The amount of change of the resistance of a material for a given change in temperature Temperature coefficient of resistance An uninterrupted, or unbroken, path for current from the source (EMF), through the load, and back to the source. Closed Circuit Incomplete circuit, exists if a break in the circuit occurs; this prevents a complete path for current flow. Open Circuit A circuit that offers very little resistance to current flow and can cause dangerously high current flow through a circuit Short Circuit Authorereim ID29541 Card SetElectrical Sciences DC Theory DescriptionDC Theory Updated2010-08-11T14:46:10Z Show Answers