(I donââ‚Âà ‚¬ÃƒÂ¢Ã¢â‚¬Å¾Ã‚¢t expect anyone to read this whole thing, but if youââ‚Âà ‚¬ÃƒÂ¢Ã¢â‚¬Å¾Ã‚¢re interested in electronics, seek and you shall find the answer. Also, if you have anything you think I should add, send me a PM.)
Electric Circuit, path of an electric current. The term is usually taken to mean a continuous path composed of conductors and conducting devices and including a source of electromotive force that drives the current around the circuit. A circuit of this type is termed a closed circuit, and a circuit in which the current path is not continuous is called an open circuit. A short circuit is a closed circuit in which a direct connection is made, with no appreciable resistance, inductance, or capacitance, between the terminals of the source of electromotive force.
Current flows in an electric circuit in accordance with several definite laws. The basic law of current flow is Ohm's law, named for its discoverer, the German physicist Georg Ohm. Ohm's law states that the amount of current flowing in a circuit made up of pure resistances is directly proportional to the electromotive force impressed on the circuit and inversely proportional to the total resistance of the circuit. The law is usually expressed by the formula I = V/R, where I is the current in amperes, V is the electromotive force in volts, and R is the resistance in ohms. Ohm's law applies to all electric circuits for both direct current (DC) and alternating current (AC), but additional principles must be invoked for the analysis of complex circuits and for AC circuits also involving inductances and capacitances.
A series circuit is one in which the devices or elements of the circuit are arranged in such a way that the entire current (I) passes through each element without division or branching into parallel circuits.
When two or more resistances are in series in a circuit, the total resistance may be calculated by adding the values of such resistances. If the resistances are in parallel, the total value of the resistance in the circuit is given by the formula
In a parallel circuit, electrical devices, such as incandescent lamps or the cells of a battery, are arranged to allow all positive (+) poles, electrodes, and terminals to be joined to one conductor, and all negative ( ) ones to another conductor, so that each unit is, in effect, on a parallel branch. The value of two equal resistances in parallel is equal to half the value of the component resistances, and in every case the value of resistances in parallel is less than the value of the smallest of the individual resistances involved. In AC circuits, or circuits with varying currents, circuit components other than resistance must be considered.
If a circuit has a number of interconnected branches, two other laws are applied in order to find the current flowing in the various branches. These laws, discovered by the German physicist Gustav Robert Kirchhoff, are known as Kirchhoff's laws of networks. The first of Kirchhoff's laws states that at any junction in a circuit through which a steady current is flowing, the sum of the currents flowing to the point is equal to the sum of the currents flowing away from that point. The second law states that, starting at any point in a network and following any closed path back to the starting point, the net sum of the electromotive forces encountered will be equal to the net sum of the products of the resistances encountered and the currents flowing through them. This second law is simply an extension of Ohm's law.
The application of Ohm's law to circuits in which there is an alternating current is complicated by the fact that capacity and inductance are always present. Inductance makes the peak value of an alternating current lag behind the peak value of voltage; capacitance makes the peak value of voltage lag behind the peak value of the current. Capacitance and inductance inhibit the flow of alternating current and must be taken into account in calculating current flow. The current in AC circuits can be determined graphically by means of vectors or by means of the algebraic equation
in which L is inductance, C is capacitance, and f is the frequency of the current. The quantity in the denominator of the fraction is called the impedance of the circuit to alternating current and is sometimes represented by the letter Z; then Ohm's law for AC circuits is expressed by the simple equation I = V/Z.
Circuit Board, flat piece of nonconductive material on which computer microprocessors and other electric components are mounted and electrically connected by thin strips of metal.
Wi-Fi, an abbreviation for wireless fidelity, is a wireless communication technology that can provide connections between portable computers and wired connections to the Internet. To connect users with the Internet, Wi Fi devices use low power transmitters and receivers equipped with special computer chips containing radio modems. The chips can be installed in laptop computers, personal digital assistants (PDAs), and cellular telephones.
Radio modems provide the same functions as modems that operate with conventional wire based networks: They modulate and demodulate signals to mimic digital bit streams, the same format used by computers. Wi Fi equipped computers, cell phones, and PDAs provide mobile, wireless access to e mail and Internet sites. The radio modems must be in range of a Wi Fi device containing a transmitter and receiver that is connected to a landline providing Internet access. Areas within range of a Wi Fi transmitter and receiver are known as hot spots. Current technical standards limit the range to distances of about 90 m (300 ft). Many transmitters, however, can be linked to cover a wider area, such as an airport or hotel. Current Wi Fi standards enable data to be sent at high speeds ranging from 11 to 54 megabits per second. This is known as a broadband connection because a vast amount of data can be sent quickly. A new technology known as WiMax promises to extend the range of a transmitter and receiver to about 48 km (30 mi). The WiMax technology also expands the capabilities of broadband connections by enabling users to remain connected to Internet hot spots even when traveling in an automobile or train at speeds up to 250 km/h (155 mph).
Capacitors, or electrical condenser, device for storing an electrical charge. In its simplest form a capacitor consists of two metal plates separated by a nonconducting layer called the dielectric. When one plate is charged with electricity from a direct current or electrostatic source, the other plate will have induced in it a charge of the opposite sign; that is, positive if the original charge is negative and negative if the charge is positive. The Leyden jar is a simple form of capacitor in which the two conducting plates are metal foil coatings on the inside and outside of a glass bottle or jar that serves as the dielectric. The electrical size of a capacitor is its capacitance, the amount of electric charge it can hold.
Capacitors are limited in the amount of electric charge they can absorb; they can conduct direct current for only an instant but function well as conductors in alternating current circuits. This property makes them useful when direct current must be prevented from entering some part of an electric circuit. Fixed capacity and variable capacity capacitors are used in conjunction with coils as resonant circuits in radios and other electronic equipment. Large capacitors are also employed in power lines to resonate the load on the line and make it possible for the line to transmit more power.
Capacitors are produced in a wide variety of forms. Air, mica, ceramics, paper, oil, and vacuums are used as dielectrics, depending on the purpose for which the device is intended.
I think I should include some HTML and other programming language descriptions in this, so if you are big on that kind of stuff, email me at
nonom329@aim.com
P.S. Hope this helps!! I have more to add but I could not get in in one post...