Science

By Tim Tolbert Continued from Alternating Current - Part 1 ... Frequency The number of cycles of AC per second is referred to as the Frequency , and is measured in Hertz. Most AC equipment are rated by frequency as well as by voltage and current. A cycle consists of two complete alternations in a period of time. The term HERTZ (Hz) has been designated to indicate one cycle per second. If one cycle per second is one hertz, then 100 cycles per second are equal to 100 hertz, and so on. In the previous example above, if the loop makes one complete revolution each second, the generator produces one complete cycle of AC during each second (1 Hz). Increasing the number of revolutions to two per second will produce two complete cycles of AC per second (2 Hz). The number of complete cycles of alternating current or voltage completed each second is referred to as the Frequency . Frequency is always measured and expressed in hertz. Alternating-current frequency is an important term to un...

By Tim Tolbert In this blog post I would like to explain the overall basics of what Alternating Current (AC) is, and how it is made and used, as I currently understand it to be. Current that regularly changes direction is called Alternating Current (AC). Alternating current is current which constantly changes in amplitude (value), and which reverses direction at regular intervals (polarity of value). Direct current flows in one direction only, while alternating current is constantly changing in amplitude (value) and direction (polarity). With direct current (DC), current flows only in one direction (from the negative terminal, through the circuit, to the positive terminal), and the amplitude of current is determined by the number of electrons flowing past a point in a circuit in one second. If, for example, a coulomb of electrons moves past a point in a wire in one second and all of the electrons are moving in the same direction, the amplitude of direct current in the wire is one...

By Tim Tolbert Continued from Direct Current - Part 2 ... Parallel DC Circuits A Parallel Circuit is defined as a circuit having more than one current path connected to a common voltage source. Therefore parallel circuits must contain at least two or more resistances which are not connected in series. In a parallel circuit, the same voltage is present in each branch (a branch is a section of a circuit that has a complete path for current). The voltage is equal to the applied voltage (E s ), and expressed in equation form as:   E s = E R1 = E R2     Parallel DC Circuit Ohm's law states that the current in a circuit is inversely proportional to the circuit resistance. This fact is true in both series and parallel circuits. There is a single path for current in a series circuit, and the amount of current is determined by the total resistance of the circuit and the applied voltage. In a parallel circuit the source current divides among the available p...

By Tim Tolbert Continued from Direct Current - Part 1 ... Series DC Circuits When two unequal charges are connected by a conductor, a complete pathway for current exists. An electric circuit is a complete conducting pathway. It consists not only of the conductor, but also includes the path through the voltage source. Inside the voltage source, the current flows from the positive terminal through the source itself and then emerges at the negative terminal. Outside the voltage source, the current flows from the voltage sources negative terminal, through the circuit, and then to the connected voltage sources positive terminal. A Series Circuit is defined as a circuit that contains only one path for current flow. Series DC Circuit Resistance in a Series Circuit In a series circuit, the total circuit resistance (R T ) is equal to the sum of the individual resistances. Therefore, for a series circuit: R T = R 1 + R 2 + R 3 + ... R n     where the subscri...

By Tim Tolbert In this blog post I would like to explain the overall basics of what Direct Current (DC) is, and how it is made and used, as I currently understand it to be. Direct Current, abbreviated as DC, is an electric current that flows in one direction only. This means that whenever a conductor is connected between the two terminals of a DC power source (such as a battery, for example, since battery cells are DC power sources), the electrons flow from one terminal (negative) of the DC power source to the other terminal (positive) of the DC power source through the conductor continuously without reversing the direction of electron flow. To understand the effects that direct current has on an electrical circuit, the relationship that exists between the different properties of electricity (current, voltage, resistance, etc..) must be understood. Some examples of Direct Current (DC) power sources include: Batteries & Cells Solar Cells & Panels Thermocouples ...

By Tim Tolbert Continued from Batteries - Part 1 ... BATTERIES A battery is a voltage source that uses chemical action to produce a voltage. In many cases the term battery is applied to a single cell, such as a flashlight battery. In the case of a flashlight that uses a battery of 1.5 volts, the battery is a single cell. For batteries that provide more voltage than a single cell can provide, that battery is composed of multiple cells to provide the total amount required of it. If a cell is manufactured so that it provides 2 volts, then a 12 volt battery consisting of those cells would contain six 2 volt cells. Therefore, a battery is a device that combines one or more cells to provide a specific voltage output. There are three ways to combine cells to form a battery: Series-Connected Cells : Cells connected in Series provide a higher voltage, Parallel-Connected Cells : Cells connected in Parallel provide a higher current capacity, Series-Parallel-Connected Cells (Complex...