* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Basic Electricity
Resistive opto-isolator wikipedia , lookup
Three-phase electric power wikipedia , lookup
Ground (electricity) wikipedia , lookup
Switched-mode power supply wikipedia , lookup
Skin effect wikipedia , lookup
War of the currents wikipedia , lookup
Voltage optimisation wikipedia , lookup
Current source wikipedia , lookup
Mercury-arc valve wikipedia , lookup
Buck converter wikipedia , lookup
Electric machine wikipedia , lookup
Opto-isolator wikipedia , lookup
Earthing system wikipedia , lookup
Power engineering wikipedia , lookup
Semiconductor device wikipedia , lookup
Rectiverter wikipedia , lookup
Stray voltage wikipedia , lookup
History of electromagnetic theory wikipedia , lookup
Mains electricity wikipedia , lookup
Electrification wikipedia , lookup
Basic Electricity Electricity is the energy that makes everything from toasters to televisions work. It is also linked to magnetism. Together, as electromagnetism, they are one of the four fundamental forces holding the Universe together. • Most electricity is generated in power stations by magnets that spin between coils of wire to induce an electric current. • The magnets are turned by turbines, which are themselves either turned by steam heated by burning coal, oil or gas, or by nuclear fuel, or turned by wind or water. • The stronger the magnet, the faster it turns, the more coils there are, so the bigger the voltage created. The four basic concepts we need electricity as relates to audio. • Voltage • Current • Resistance • Power An electric charge that does not move is called static electricity. A charge may flow in a current providing there is an unbroken loop, or circuit. A current only flows through a good conductor such as copper, namely a material that transmits charge well. A current only flows if there is a driving force to push the charge. This force is called an electromotive force (emf). The emf is created by a battery or a generator. Currents were once thought to flow like water. In fact they move like a row of marbles knocking into each other. In a good conductor there are lots of free electrons that are unattached to atoms. These are the ‘marbles. A current only flows if there are more electrons at one point in the circuit. This difference, called the potential difference, is measured in volts. The rate at which current flows is measured in amps. It depends on the voltage and the resistance (how much the circuit obstructs the flow of current). Resistance is measured in ohms. Voltage Electric potential difference, potential drop, electromotive force, electric tension... Voltage is commonly referred to as electrical pressure. An analogy that is often used is that voltage is like the pressure of water which is stored in a dam. Measured at the base, the water has tremendous pressure, regardless of whether or not it is flowing. Voltage is the potential for current in the same way water pressure is the potential for flow. Voltage is the force which causes current to flow through an electronic circuit. Two sources of voltage are batteries and general power outlets. Current • All substances in the universe are made up of atoms. • Atoms are made of protons (+ve charge), neutrons, (neutral charge), and electrons (ve charge). Apparently all of the above are made of quarks but I've never seen them so... Who knows. It's not that important in audio. The electrons are the important thing here: they collect around the central part of the atom and the number of electrons around the atom will give an atom its overall negative or positive charge. Nature always seeks balance, and some types of atoms will "give up" their electrons easily in order to balance with other atoms next to them. That means that some substances conduct electricity, which is simply electrical charge, easilysubstances like copper, gold, silver. These substances are conductors. Some are very stable, and do not give away their electrons easily, substances like rubber and plastic. These substances are insulators. That is why audio and electrical cables are constructed the way they are. Electrical current passes along the conductive element and is contained within an insulative substance which protects the outside world from current, and guides the electricity along the desired path as well as protecting the electricity, which is also our audio signal after all, from interference. current flow: Direct current and Alternating current. Direct current means current flows in one direction, from negative to positive. The most common type of Direct current is used to charge batteries, and in nearly all electronic systems, as the power supply. Very large quantities of directcurrent power are used in production of aluminum and other electrochemical processes. Direct current is used for some railway propulsion, especially in urban areas. Highvoltage direct current is used to transmit large amounts of power from remote generation sites or to interconnect alternating current power grids. Like the difference in height between the top of the dam and the bottom, there is an excess of electrons within the minus portion of the battery, which is expressed as voltage (AA battery is 1.5v for example) Because its a one way flow, the charge depletes and runs out. Direct current may flow in a conductor such as a wire, but can also flow through semiconductors, insulators, or even through a vacuum as in electron or ion beams. The electric charge flows in a constant direction, distinguishing it from alternating current (AC). The detailed movement of electrons in AC current gets very complex and depends on the exact conductor being used but, simplistically, the electrons simply move back and forth (away from and then towards the generator) over a short space If you think of DC as a push system analogous to a straight flow of water in a hose, then AC is a push-pull system which would be like water in a hose connected to a piston that, as the piston cycles, first pushes the water down the hose and then sucks it back. In a DC water hose, a molecule of water can only perform work e.g. moving a turbine, when it travels from one end of the hose to the other. However, in an AC water hose, a molecule of water just oscillates around its starting location and it is just the force of the molecule hitting the next molecule in the chain that transmits the energy. The last molecule in the chain is always the one that strikes the turbine and performs the work. That is why AC can transmit energy over long distances. In DC, the generator must push an electron all the way down the wire to the load (and eventually back down the other side of the circuit) to perform any work. AC by contrast is just transmitting the electro repulsive force that drive electrons away from each other. (Just like a Newton's cradle transmits momentum instead of moving the spheres.) Fun Facts Two positive charges repel each other, as do two negative charges. Opposite charges on the other hand, attract each other. When an electric charge builds up on the surface of an object it creates static electricity. You have probably experienced static electricity in the form of a small electric shock, which is what happens when the electric charge is quickly neutralized by an opposite charge. Electric eels can produce strong electric shocks of around 500 volts for both self defense and hunting. Electric circuits can contain parts such as switches, transformers, resistors and transformers.A common way to produce electricity is by hydropower, a process that generates electricity by using water to spin turbines attached to generators. Lightning is a discharge of electricity in the atmosphere. Lightning bolts can travel at around 210,000 kph (130,000 mph), while reaching nearly 30,000 °C (54,000 °F) in temperature. Electric fields work in a similar way to gravity with an important exception being that while gravity always attracts, electric fields can either attract or repulse. American Benjamin Franklin carried out extensive electricity research in the 18th century, inventing the lightning rod amongst his many discoveries. Lightning rods protect buildings in the event of lightning by conducting lightning strikes through a grounded wire. Back in the 1880’s there was even a ‘war of currents’ between Thomas Edison (who helped invent DC) and Nikola Tesla (who helped invent AC). Both wanted their system to be used with AC eventually winning out due to the fact that it is safer and can be used over longer distances. Alternating current is the type available from a GPO. Alternating current changes polarity at regular intervals. House current changes direction 60 times per second. The way in which power changes direction can be observed on an oscilloscope and looks like a sine wave of 60 cycles per second or 60Hz. So, "60 cycle hum" is the sound of AC current leaking into the audio chain somewhere along the line. Loads Why do I have to know about power and electricity, when all I am doing is mixing music? Because this can happen. Uluru gala dinner 31/7/13 To be continued…..