Electricity

Electricity
1. Electricity is the set of physical phenomena associated with the presence and flow of electric charge. Electricity gives a wide variety of well known effects, such as lightning, static electricity, electromagnetic induction and electrical current. In addition, electricity permits the creation and reception of electromagnetic radiation such as radio waves.In electricity, charges produce electromagnetic fields which act on other charges. .....
Electric charge
2. The presence of charge gives rise to an electrostatic force charges exert a force on each other, an effect that was known, though not understood, in antiquity.A lightweight ball suspended from a string can be charged by touching it with a glass rod that has itself been charged by rubbing with a cloth. If a similar ball is charged by the same glass rod, it is found to repel the first the charge acts to force the two balls apart. Two balls that are charged with a rubbed amber rod also repel each other. However, if one ball is charged by the glass rod, and the other by an amber rod, the two balls are found to attract each other. These phenomena were investigated in the late eighteenth century by Charles Augustin de Coulomb, who deduced that charge manifests itself in two opposing forms. This discovery led to the well known axiom like charged objects repel and opposite charged objects attract.

The force acts on the charged particles themselves, hence charge has a tendency to spread itself as evenly as possible over a conducting surface. The magnitude of the electromagnetic force, whether attractive or repulsive, is given by Coulombs law, which relates the force to the product of the charges and has an inverse square relation to the distance between them.The electromagnetic force is very strong, second only in strength to the strong interaction, but unlike that force it operates over all distances.In comparison with the much weaker gravitational force, the electromagnetic force pushing two electrons apart is 1042 times that of the gravitational attraction pulling them together.

Study has shown that the origin of charge is from certain types of subatomic particles which have the property of electric charge. Electric charge gives rise to and interacts with the electromagnetic force, one of the four fundamental forces of nature. The most familiar carriers of electrical charge are the electron and proton. Experiment has shown charge to be a conserved quantity, that is, the net charge within an isolated system will always remain constant regardless of any changes taking place within that system.within the system, charge may be transferred between bodies, either by direct contact, or by passing along a conducting material, such as a wire.2 5 The informal term static electricity refers to the net presence or imbalance of charge on a body, usually caused when dissimilar materials are rubbed together, transferring charge from one to the other.

The charge on electrons and protons is opposite in sign, hence an amount of charge may be expressed as being either negative or positive. By convention, the charge carried by electrons is deemed negative, and that by protons positive, a custom that originated with the work of Benjamin Franklin.The amount of charge is usually given the symbol Q and expressed in coulombs;each electron carries the same charge of approximately ?1.6022?10?19 coulomb. The proton has a charge that is equal and opposite, and thus +1.6022?10?19 coulomb. Charge is possessed not just by matter, but also by antimatter, each antiparticle bearing an equal and opposite charge to its corresponding particle.

Charge can be measured by a number of means, an early instrument being the gold leaf electroscope, which although still in use for classroom demonstrations, has been superseded by the electronic electrometer. .....

Electric current
3. The movement of electric charge is known as an electric current, the intensity of which is usually measured in amperes. Current can consist of any moving charged particles; most commonly these are electrons, but any charge in motion constitutes a current.

By historical convention, a positive current is defined as having the same direction of flow as any positive charge it contains, or to flow from the most positive part of a circuit to the most negative part. Current defined in this manner is called conventional current. The motion of negatively charged electrons around an electric circuit, one of the most familiar forms of current, is thus deemed positive in the opposite direction to that of the electrons. However, depending on the conditions, an electric current can consist of a flow of charged particles in either direction, or even in both directions at once. The positive to negative convention is widely used to simplify this situation.The process by which electric current passes through a material is termed electrical conduction, and its nature varies with that of the charged particles and the material through which they are travelling. Examples of electric currents include metallic conduction, where electrons flow through a conductor such as metal, and electrolysis, where ions charged atoms flow through liquids, or through plasmas such as electrical sparks. While the particles themselves can move quite slowly, sometimes with an average drift velocity only fractions of a millimetre per second,the electric field that drives them itself propagates at close to the speed of light, enabling electrical signals to pass rapidly along wires.

Current causes several observable effects, which historically were the means of recognising its presence. That water could be decomposed by the current from a voltaic pile was discovered by Nicholson and Carlisle in 1800, a process now known as electrolysis. Their work was greatly expanded upon by Michael Faraday in 1833. Current through a resistance causes localised heating, an effect James Prescott Joule studied mathematically in 1840. One of the most important discoveries relating to current was made accidentally by Hans Christian .....

Electric field
4. The concept of the electric field was introduced by Michael Faraday. An electric field is created by a charged body in the space that surrounds it, and results in a force exerted on any other charges placed within the field. The electric field acts between two charges in a similar manner to the way that the gravitational field acts between two masses, and like it, extends towards infinity and shows an inverse square relationship with distance. However, there is an important difference. Gravity always acts in attraction, drawing two masses together, while the electric field can result in either attraction or repulsion. Since large bodies such as planets generally carry no net charge, the electric field at a distance is usually zero. Thus gravity is the dominant force at distance in the universe, despite being much weaker.

Field lines emanating from a positive charge above a plane conductor An electric field generally varies in space, and its strength at any one point is defined as the force per unit charge that would be felt by a stationary, negligible charge if placed at that point.469 470 The conceptual charge, termed a test charge, must be vanishingly small to prevent its own electric field disturbing the main field and must also be stationary to prevent the effect of magnetic fields. As the electric field is defined in terms of force, and force is a vector, so it follows that an electric field is also a vector, having both magnitude and direction. Specifically, it is a vector field.

The study of electric fields created by stationary charges is called electrostatics. The field may be visualised by a set of imaginary lines whose direction at any point is the same as that of the field. This concept was introduced by Faraday, whose term lines of force still sometimes sees use. The field lines are the paths that a point positive charge would seek to make as it was forced to move within the field; they are however an imaginary concept with no physical existence, and the field permeates all the intervening space between the lines. Field lines emanating from stationary charges have several key properties first, that they originate at positive charges and terminate at negative charges; second, that they must enter any good conductor at right angles, and third, that they may never cross nor close in on themselves.

A hollow conducting body carries all its charge on its outer surface. The field is therefore zero at all places inside the body.88 This is the operating principal of the Faraday cage, a conducting metal shell which isolates its interior from outside electrical effects.

The principles of electrostatics are important when designing items of high voltage equipment. There is a finite limit to the electric field strength that may be withstood by any medium. Beyond this point, electrical breakdown occurs and an electric arc causes flashover between the charged parts. Air, for example, tends to arc across small gaps at electric field strengths which exceed 30 kV per centimetre. Over larger gaps, its breakdown strength is weaker, perhaps 1 kV per centimetre.The most visible natural occurrence of this is lightning, caused when charge becomes separated in the clouds by rising columns of air, and raises the electric field in the air to greater than it can withstand. The voltage of a large lightning cloud may be as high as 100 MV and have discharge energies as great as 250 kWh.

The field strength is greatly affected by nearby conducting objects, and it is particularly intense when it is forced to curve around sharply pointed objects. This principle is exploited in the lightning conductor, the sharp spike of which acts to encourage the lightning stroke to develop there, rather than to the building it serves to protect155. .....

Electric potential
5. The concept of electric potential is closely linked to that of the electric field. A small charge placed within an electric field experiences a force, and to have brought that charge to that point against the force requires work. The electric potential at any point is defined as the energy required to bring a unit test charge from an infinite distance slowly to that point. It is usually measured in volts, and one volt is the potential for which one joule of work must be expended to bring a charge of one coulomb from infinity.This definition of potential, while formal, has little practical application, and a more useful concept is that of electric potential difference, and is the energy required to move a unit charge between two specified points. An electric field has the special property that it is conservative, which means that the path taken by the test charge is irrelevant all paths between two specified points expend the same energy, and thus a unique value for potential difference may be stated.The volt is so strongly identified as the unit of choice for measurement and description of electric potential difference that the term voltage sees greater everyday usage.

For practical purposes, it is useful to define a common reference point to which potentials may be expressed and compared. While this could be at infinity, a much more useful reference is the Earth itself, which is assumed to be at the same potential everywhere. This reference point naturally takes the name earth or ground. Earth is assumed to be an infinite source of equal amounts of positive and negative charge, and is therefore electrically uncharged .....

Electromagnets
6. .....
Electrochemistry
7. The ability of chemical reactions to produce electricity, and conversely the ability of electricity to drive chemical reactions has a wide array of uses. Electrochemistry has always been an important part of electricity. From the initial invention of the Voltaic pile, electrochemical cells have evolved into the many different types of batteries, electroplating and electrolysis cells. Aluminium is produced in vast quantities this way, and many portable devices are electrically powered using rechargeable cells. .....
Electric circuits
8. An electric circuit is an interconnection of electric components such that electric charge is made to flow along a closed path a circuit, usually to perform some useful task. The components in an electric circuit can take many forms, which can include elements such as resistors, capacitors, switches, transformers and electronics. Electronic circuits contain active components, usually semiconductors, and typically exhibit non linear behaviour, requiring complex analysis. The simplest electric components are those that are termed passive and linear while they may temporarily store energy, they contain no sources of it, and exhibit linear responses to stimuli.

The resistor is perhaps the simplest of passive circuit elements as its name suggests, it resists the current through it, dissipating its energy as heat. The resistance is a consequence of the motion of charge through a conductor in metals, for example, resistance is primarily due to collisions between electrons and ions. Ohms law is a basic law of circuit theory, stating that the current passing through a resistance is directly proportional to the potential difference across it. The resistance of most materials is relatively constant over a range of temperatures and currents; materials under these conditions are known as ohmic. The ohm, the unit of resistance, was named in honour of Georg Ohm, and is symbolised by the Greek letter ?. 1 ? is the resistance that will produce a potential difference of one volt in response to a current of one amp.

The capacitor is a development of the Leyden jar and is a device that can store charge, and thereby storing electrical energy in the resulting field. It consists of two conducting plates separated by a thin insulating dielectric layer; in practice, thin metal foils are coiled together, increasing the surface area per unit volume and therefore the capacitance. The unit of capacitance is the farad, named after Michael Faraday, and given the symbol F one farad is the capacitance that develops a potential difference of one volt when it stores a charge of one coulomb. A capacitor connected to a voltage supply initially causes a current as it accumulates charge; this current will however decay in time as the capacitor fills, eventually falling to zero. A capacitor will therefore not permit a steady state current, but instead blocks it.

The inductor is a conductor, usually a coil of wire, that stores energy in a magnetic field in response to the current through it. When the current changes, the magnetic field does too, inducing a voltage between the ends of the conductor. The induced voltage is proportional to the time rate of change of the current. The constant of proportionality is termed the inductance. The unit of inductance is the henry, named after Joseph Henry, a contemporary of Faraday. One henry is the inductance that will induce a potential difference of one volt if the current through it changes at a rate of one ampere per second. The inductors behaviour is in some regards converse to that of the capacitor it will freely allow an unchanging current, but opposes a rapidly changing one. .....

Electric power
9. Electric power is the rate at which electric energy is transferred by an electric circuit. The SI unit of power is the watt, one joule per second.
Electric power, like mechanical power, is the rate of doing work, measured in watts, and represented by the letter P. The term wattage is used colloquially to mean electric power in watts. The electric power in watts produced by an electric current I consisting of a charge of Q coulombs every t seconds passing through an electric potential voltage difference of V is
P = text{work done per unit time} = frac {QV}{t} = IV ,
where
Q is electric charge in coulombs
t is time in seconds
I is electric current in amperes
V is electric potential or voltage in volts
Electricity generation is often done with electric generators, but can also be supplied by chemical sources such as electric batteries or by other means from a wide variety of sources of energy. Electric power is generally supplied to businesses and homes by the electric power industry. Electricity is usually sold by the kilowatt hour 3.6 MJ which is the product of power in kilowatts multiplied by running time in hours. Electric utilities measure power using electricity meters, which keep a running total of the electric energy delivered to a customer. .....
Electronics
10. Electronics deals with electrical circuits that involve active electrical components such as vacuum tubes, transistors, diodes and integrated circuits, and associated passive interconnection technologies. The nonlinear behaviour of active components and their ability to control electron flows makes amplification of weak signals possible and electronics is widely used in information processing, telecommunications, and signal processing. The ability of electronic devices to act as switches makes digital information processing possible. Interconnection technologies such as circuit boards, electronics packaging technology, and other varied forms of communication infrastructure complete circuit functionality and transform the mixed components into a regular working system.

Today, most electronic devices use semiconductor components to perform electron control. The study of semiconductor devices and related technology is considered a branch of solid state physics, whereas the design and construction of electronic circuits to solve practical problems come under electronics engineering. .....

Electromagnetic wave
11. Faradays and Amp .....
Generation and transmission
12. In the 6th century BC, the Greek philosopher Thales of Miletus experimented with amber rods and these experiments were the first studies into the production of electrical energy. While this method, now known as the triboelectric effect, can lift light objects and generate sparks, it is extremely inefficient. It was not until the invention of the voltaic pile in the eighteenth century that a viable source of electricity became available. The voltaic pile, and its modern descendant, the electrical battery, store energy chemically and make it available on demand in the form of electrical energy. The battery is a versatile and very common power source which is ideally suited to many applications, but its energy storage is finite, and once discharged it must be disposed of or recharged. For large electrical demands electrical energy must be generated and transmitted continuously over conductive transmission lines.

Electrical power is usually generated by electro mechanical generators driven by steam produced from fossil fuel combustion, or the heat released from nuclear reactions; or from other sources such as kinetic energy extracted from wind or flowing water. The modern steam turbine invented by Sir Charles Parsons in 1884 today generates about 80 percent of the electric power in the world using a variety of heat sources. Such generators bear no resemblance to Faradays homopolar disc generator of 1831, but they still rely on his electromagnetic principle that a conductor linking a changing magnetic field induces a potential difference across its ends. The invention in the late nineteenth century of the transformer meant that electrical power could be transmitted more efficiently at a higher voltage but lower current. Efficient electrical transmission meant in turn that electricity could be generated at centralised power stations, where it benefited from economies of scale, and then be despatched relatively long distances to where it was needed. .....

Physiological effects
13. A voltage applied to a human body causes an electric current through the tissues, and although the relationship is non linear, the greater the voltage, the greater the current.The threshold for perception varies with the supply frequency and with the path of the current, but is about 0.1 mA to 1 mA for mains frequency electricity, though a current as low as a microamp can be detected as an electrovibration effect under certain conditions.If the current is sufficiently high, it will cause muscle contraction, fibrillation of the heart, and tissue burns.The lack of any visible sign that a conductor is electrified makes electricity a particular hazard. The pain caused by an electric shock can be intense, leading electricity at times to be employed as a method of torture. Death caused by an electric shock is referred to as electrocution. Electrocution is still the means of judicial execution in some jurisdictions, though its use has become rarer in recent times. .....
Electricity in physics
14. Electricity works because electric charges push and pull on each other. There are two types of electric charges positive charges and negative charges. Similar charges repel each other. This means that if you put two positive charges close together and let them go, they would move apart. Two negative charges also repel. But different charges attract each other. This means that if you put a positive charge and a negative charge close together, they would smack together. A short way to remember this is the phrase opposites attract, likes repel.

Electric charges push or pull on each other if they are not touching. This is possible because each charge makes an electric field around itself. An electric field is an area that surrounds a charge. At each point near a charge, the electric field points in a certain direction. If a positive charge is put at that point, it will be pushed in that direction. If a negative charge is put at that point, it will be pushed in the exact opposite direction.

All the matter in the world is made of tiny positive and negative charges. The positive charges are called protons, and the negative charges are called electrons. Protons are much bigger and heavier than electrons, but they both have the same amount of electric charge, except that protons are positive and electrons are negative. Because opposites attract, protons and electrons stick together. A few protons and electrons can form bigger particles called atoms and molecules. Atoms and molecules are still very tiny. It is impossible to see them without a very powerful microscope. Any big object, like your body, has more atoms and molecules in it than anyone could count.

Because negative electrons and positive protons stick together to make big objects, all big objects that we can see and feel are electrically neutral. Electrically is a word meaning describing electricity, and neutral is a word meaning balanced. That is why we do not feel objects pushing and pulling on us from a distance, like they would if everything was electrically charged. All big objects are electrically neutral because there is exactly the same amount of positive and negative charge in the world. We could say that the world is exactly balanced, or neutral. This seems very surprising and lucky. Scientists still do not know why this is so, even though they have been studying electricity for a long time. .....

Electric voltage
15. Electric voltage is the push behind the current. It is the amount of work per electric charge that an electric source can do. When 1 coulomb of electricity has 1 joule of energy, it will have 1 volt of electric potential. .....
Electrical resistance
16. Electrical resistance is the ability of a substance to resist the flowing of the current, i.e. to reduce the amount of current that flows through the substance. If an electric voltage of 1 volt maintains a current of 1 ampere through a wire, the resistance of the wire is 1 ohm. When the flow of current is opposed resisted energy gets used or gets converted to other forms e.g. heat, etc.. .....
Electric energy
17. Electric energy is the ability to do work by means of electric devices. Electric energy is a conserved property, meaning that it behaves like a substance and can be moved from place to place. Electric energy is measured in joules or kilowatt hours kW h. .....
Generating electricity
18. Electricity is mostly generated in places called power stations. Most power stations use heat to boil water into steam which turns a steam engine. The steam engines turbine turns a machine called a generator. Generators have wires inside which spin inside a magnetic field. Electromagnetic induction causes electricity to flow through the wires.

There are many sources of heat which can be used to generate electricity. Heat sources can be classified into two types renewable energy resources in which the supply of heat energy never runs out and non renewable energy resources in which the supply will be eventually used up. Sometimes a natural flow, such as wind power or water power, can be used directly to turn a generator so no heat is needed. .....

Making Electricity
19. In Michael Faradays generator, coils of copper wire rotating between the poles of a magnet produce a steady current of electricity. One way to rotate the disk is to crank it by hand, but this isnt a practical way to make electricity. Another option is to attach the shaft of the generator to a turbine and then let some other energy source power the turbine. Falling water is one such energy source, and, in fact, the first major plant ever built took advantage of the enormous kinetic energy delivered by Niagara Falls. George Westinghouse opened that plant in 1895, but the principles of its operation havent changed much since then. First, engineers build a dam across a river to create a reservoir of stored water. They place a water intake near the bottom of the dam wall, which allows water to flow from the reservoir and through a narrow channel called a penstock. The turbine imagine a huge propeller sits at the end of the penstock. The shaft from the turbine goes up into the generator. When the water moves across the turbine, it spins, rotating the shaft and, in turn, rotating the copper coils of the generator. As the copper coils spin within the magnets, electricity is produced. Power lines connected to the generator carry electricity from the power plant to homes and businesses. Westinghouses Niagara Falls plant was able to transport electricity more than 200 miles 322 kilometers. Not all power plants rely on falling water. Many take advantage of steam, which acts like a fluid and can therefore transfer energy to a turbine and, ultimately, to a generator. The most popular way to make steam is to heat water by burning coal. Its also possible to use controlled nuclear reactions to turn water into steam. You can read about the various types of power stations in How Hydropower Plants Work, How Wind Power Works and How Nuclear Power Works. Just keep in mind that they all work on the same basic principle of converting mechanical energy spinning turbine into electrical energy. Of course, using a generator to make electricity is just the beginning. After you get your electrons moving along, youll need an electrical circuit to do anything with it. Find out why next. .....
Electrical Circuits
20. When you load a battery into an electronic device, youre not simply unleashing the electricity and sending it to do a task. Negatively charged electrons wish to travel to the positive portion of the battery and if they have to rev up your personal electric shaver along the way to get there, theyll do it. On a very simple level, its much like water flowing down a stream and being forced to turn a water wheel to get from point A to point B.

Whether you are using a battery, a fuel cell or a solar cell to produce electricity, three things are always the same The source of electricity must have two terminals a positive terminal and a negative terminal. The source of electricity whether it is a generator, battery or something else will want to push electrons out of its negative terminal at a certain voltage. For example, one AA battery typically wants to push electrons out at 1.5 volts.

The electrons will need to flow from the negative terminal to the positive terminal through a copper wire or some other conductor. When there is a path that goes from the negative to the positive terminal, you have a circuit, and electrons can flow through the wire.

You can attach any type of load, such as a light bulb or motor, in the middle of the circuit. The source of electricity will power the load, and the load will perform whatever task its designed to carry out, from spinning a shaft to generating light.

Electrical circuits can get quite complex, but basically you always have the source of electricity such as a battery, a load and two wires to carry electricity between the two. Electrons move from the source, through the load and back to the source.

Moving electrons have energy. As the electrons move from one point to another, they can do work. In an incandescent light bulb, for example, the energy of the electrons is used to create heat, and the heat in turn creates light. In an electric motor, the energy in the electrons creates a magnetic field, and this field can interact with other magnets through magnetic attraction and repulsion to create motion. Because motors are so important to everyday activities and because they are, in essence, a generator working in reverse, well examine them more closely in the next section. .....

Electric Motors
21. As weve already discussed, a generator converts mechanical energy into electricity. A motor works on the same principles, but in the opposite direction it converts electrical energy into mechanical energy. To do this, a motor needs a special kind of magnet known as an electromagnet. In its simplest form, this consists of an iron bar wrapped in a coil of wire. If you pass an electric current through the wire, a magnetic field is formed in the iron bar, and it becomes a magnet, with definite north and south poles. Turn off the current, and the magnetic properties disappear. By themselves, electromagnets are useful things. You can use them to pick up metal objects, carry the objects somewhere and then drop them by just turning off the power. For example, roofers use them to pick up nails that have fallen by accident into a homeowners yard. And wrecking yards have cranes with built in electromagnets strong enough to pick up and move entire cars.

Electromagnets are especially useful when theyre placed on an axis between two stationary magnets. If the electromagnets south pole is situated against the south pole of one stationary magnet and its north pole against the north pole of the other stationary magnet, the electromagnet will rotate until opposite poles line up. This wouldnt be very helpful, except the polarity of electromagnets depends on the direction of current flow. Pass electric current in one direction, and the magnets north pole will be on one side; reverse the current flow, and the north pole will be on the opposite side. In motors, a device known as a commutator reverses the direction of flow of electric current. As the poles of the electromagnet flip back and forth, the magnet is able to rotate without interruption. This is a brief explanation of course, so you may want to read How Electric Motors Work for all of the details.

As it turns out, the mechanical energy created in an electric motor can be put to good use in a variety of machines. Many tools in your garage, appliances in your house and toys kids play with rely on motors. Some of these motors require a large current to operate. Others, such as small DC motors used in robots and models, need very little voltage or current to perform efficiently. Well continue our conversation about voltage and current in the next section. .....

Voltage Current and Resistance
22. As mentioned earlier, the number of electrons in motion in a circuit is called the current, and its measured in amps. The pressure pushing the electrons along is called the voltage and is measured in volts. If you live in the United States, the power outlets in the wall of your house or apartment deliver 120 volts each.

If you know the amps and volts involved, you can determine the amount of electricity consumed, which we typically measure in watt hours or kilowatt hours. Imagine that you plug a space heater into a wall outlet. You measure the amount of current flowing from the wall outlet to the heater, and it comes out to 10 amps. That means that it is a 1,200 watt heater. If you multiply the volts by the amps, you get the wattage. In this case, 120 volts multiplied by 10 amps equals 1,200 watts. This holds true for any electrical appliance. If you plug in a light and it draws half an amp, its a 60 watt light bulb.

Lets say that you turn on the space heater and then look at the power meter outside. The meters purpose is to measure the amount of electricity flowing into your house so that the power company can bill you for it. Lets assume we know its unlikely that nothing else in the house is on, so the meter is measuring only the electricity used by the space heater.

Your space heater is using 1.2 kilowatts 1,200 watts. If you leave the space heater on for one hour, you will use 1.2 kilowatt hours of power. If your power company charges you 10 cents per kilowatt hour, then the power company will charge you 12 cents for every hour that you leave your space heater on.

Now lets add one more factor to current and voltage resistance, which is measured in ohms. We can extend the water analogy to understand resistance, too. The voltage is equivalent to the water pressure, the current is equivalent to the flow rate and the resistance is like the pipe size. .....

Direct Current Versus Alternating Current
23. something called direct current DC. The positive and negative terminals of a battery are always, respectively, positive and negative. Current always flows in the same direction between those two terminals.

The power that comes from a power plant, on the other hand, is called alternating current AC. The direction of the current reverses, or alternates, 60 times per second in the U.S. or 50 times per second in Europe, for example. The power that is available at a wall socket in the United States is 120 volt, 60 cycle AC power.

The big advantage that alternating current provides for the power grid is the fact that it is relatively easy to change the voltage of the power, using a device called a transformer. Power companies save a great deal of money this way, using very high voltages to transmit power over long distances.

How does this work? Well, lets say that you have a power plant that can produce 1 million watts of power. One way to transmit that power would be to send 1 million amps at 1 volt. Another way to transmit it would be to send 1 amp at 1 million volts. Sending 1 amp requires only a thin wire, and not much of the power is lost to heat during transmission. Sending 1 million amps would require a huge wire.

So power companies convert alternating current to very high voltages for transmission such as 1 million volts, then drop it back down to lower voltages for distribution such as 1,000 volts, and finally down to 120 volts inside the house for safety. As you might imagine, its a lot harder to kill someone with 120 volts than with 1 million volts and most electrical deaths are prevented altogether today using GFCI outlets. To learn more, read How Power Grids Work. .....

Electrical Ground
24. When the subject of electricity comes up, you will often hear about electrical grounding, or just ground. For example, an electrical generator will say, Be sure to attach to an earth ground before using, or an appliance might warn, Do not use without an appropriate ground.

It turns out that the power company uses the Earth as one of the wires in the power system. The planet is a good conductor, and its huge, so it makes a handy return path for electrons. Ground in the power distribution grid is literally the ground thats all around you when you are walking outside. It is the dirt, rocks, groundwater and so on.

If you look at a utility pole, youll probably be able to spot a bare wire coming down the side of the pole. This connects the aerial ground wire directly to ground. Every utility pole on the planet has a bare wire like this. If you ever watch the power company install a new pole, you will see that the end of that bare wire is stapled in a coil to the base of the pole. That coil is in direct contact with the earth once the pole is installed, and is buried 6 to 10 feet 2 to 3 meters underground. If you examine a pole carefully, you will see that the ground wire running between poles are attached to this direct connection to ground.

Similarly, near the power meter in your house or apartment there is a 6 foot 2 meter long copper rod driven into the ground. The ground plugs and all the neutral plugs of every outlet in your house connect to this rod. Our article How Power Grids Work also talks about this. .....

Everything Is Made Of Atoms
25. Imagine a pure gold ring. Divide it in half and give one of the halves away. Keep dividing and dividing and dividing. Soon you will have a piece so small you will not be able to see it without a microscope. It may be very, very small, but it is still a piece of gold.

If you could keep dividing it into smaller and smaller pieces, you would finally get to the smallest piece of gold possible. It is called an atom. If you divided it into smaller pieces, it would no longer be gold. Everything around us is made of atoms and scientists so far know of 118 different kinds. These different kinds of atoms are called elements. There are 98 elements that exist naturally although some are only found in very small amounts. Four of these 118 elements have reportedly been discovered, but have not yet been confirmed. Atoms join together in many different combinations to form molecules, and create all of the materials you see around you. .....

Electrical Charges
26. Protons, neutrons and electrons are very different from each other. They have their own properties, or characteristics. One of these properties is called an electrical charge. Protons have what we call a positive + charge. Electrons have a negative charge. Neutrons have no charge, they are neutral.

The charge of one proton is equal in strength to the charge of one electron. When the number of protons in an atom equals the number of electrons, the atom itself has no overall charge, it is neutral. .....

Types of electricity
27. There are two types of Electricity, Static Electricity and Current Electricity. Static Electricity is made by rubbing together two or more objects and making friction while Current electricity is the flow of electric charge across an electrical field.

Static Electricity

Static electricity is when electrical charges build up on the surface of a material. It is usually caused by rubbing materials together. The result of a build up of static electricity is that objects may be attracted to each other or may even cause a spark to jump from one to the other. For Example rub a baloon on a wool and hold it up to the wall. Before rubbing, like all materials, the balloons and the wool sweater have a neutral charge. This is because they each have an equal number of positively charged subatomic particles protons and negatively charged subatomic particles electrons. When you rub the balloon with the wool sweater, electrons are transferred from the wool to the rubber because of differences in the attraction of the two materials for electrons. The balloon becomes negatively charged because it gains electrons from the wool, and the wool becomes positively charged because it loses electrons.

Current Electricity

Current is the rate of flow of electrons. It is produced by moving electrons and it is measured in amperes. Unlike static electricity, current electricity must flow through a conductor, usually copper wire. Current with electricity is just like current when you think of a river. The river flows from one spot to another, and the speed it moves is the speed of the current. With electricity, current is a measure of the amount of energy transferred over a period of time. That energy is called a flow of electrons. One of the results of current is the heating of the conductor. When an electric stove heats up, its because of the flow of current. There are different sources of current electricity including the chemical reactions taking place in a battery. The most common source is the generator. A simple generator produces electricity when a coil of copper turns inside a magnetic field. In a power plant, electromagnets spinning inside many coils of copper wire generate vast quantities of current electricity. There are two main kinds of electric current. Direct DC and Alternating AC. Its easy to remember. Direct current is like the energy you get from a battery. Alternating current is like the plugs in the wall. The big difference between the two is that DC is a flow of energy while AC can turn on and off. AC reverses the direction of the electrons. .....

Wires conduct electricity
28. Some atoms have electrons that can flow easily from one atom to another, such as metal. This is why metal is used in wires that conduct electricity. Other materials, such as rubber, have atoms that resist the flow of electricity, and that .....
Protons
29. These parts of an atom have a positive charge. They are in the middle of the atom, called the nucleus and they do not move. .....
Neutrons
30. These parts of an atom have no charge. They are neutral and part of the nucleus of an atom with the protons. .....
Electrons
31. These parts of the atom are very small and weigh a lot less then the protons and neurtons. Electrons are not part of the nucleus of the atom, instead they move around in orbits outside the nucleus. Electrons are the only part of an atom that moves. .....
Top Cricket Umpires in the world
Simon Taufel. Simon James Arthur Taufel or Simon Taufel was born on 21 January 1971 in St Leonards, New South Wales. Before starting his umpiring journey, Taufel played as a fast medium bowler for Cammeray Cricket Club in the Northern Suburbs Cricket Association. .....
World Architecture
Vehicle Assembly Building John F Kennedy Space Center. Merritt Island, Florida The U.S. National Aeronautics and Space Administration (NASA) was founded in 1958 with a brief to plan and conduct nonmilitary aeronautical and space activities and to develop international space programs. The 140,000-acre (5 .....
Benefits of Fenugreek Seeds and Leaves
Fenugreek Natural Remedies. Fenugreek seeds are rich in vitamin E and are added as preservatives in pickles.Dried leaves of the fenugreek are used for flavoring meat, fish and vegetable dishes. .....
Crazy Facts
That s not Ice Cream. Weird Foods Can you believe It, it is Chicken!? Mechanically separated chicken!? Machines here pulverize chicken?bones and everything else left behind after chickens are butchered to produce this pink goop!? It then becomes the main ingredient in pr .....
Benefits of Jackfruits
Cooking. Jackfruit flesh can be boiled and salted and served like a vegetable. It can be eaten before the fruit is fully ripe or when it is ripened. When not quite ripe, the jackfruit flesh will produce a gummy substance. Jackfruit has been used in both savor .....
Forever Young Naturally Lifestyle
Protecting bones Walk with sticks. Nordic walking (using poles to work the arms and upper body) is said by practitioners to engage 90 percent of skeletal muscles. Running uses 70; swimming a mere 35. Enrol in a class to learn the technique and hook up with a group of enthusiasts. .....
Heena Mehandi Designs
Heena Design 9. A simple yet beautiful design for those who want the mehendi to be minimal yet beautiful.The design is perfect for Eid and small functions. .....
Mysterious Caves of India
Borra Caves Ananthagiri Hills Andhra Pradesh 1. The name comes from Borra Guhalu in Telugu Borra means something that has bored into the ground and guhalu means caves. They are located in the Ananthagiri hills of the Araku valley of the Visakhapatnam district in Andhra Pradesh. In 1807, William K .....
Step to finding your perfect man
Stop being a negative nancy. Before you leave the house, stand before the mirror, look yourself in the eye and tell yourself you will find someone who inspires, excites and challenges you. .....
Benefits of Gooseberry
Amla is a deciduous tree. Amla is a deciduous tree that grows up to 20 to 30 feet high. Its botanical name is Phyllanthus emblica or Emblica officinalis. The tree is usually found in India and Nepal and this is why it is often referred to as the Indian or Nepalese gooseberry. .....
Benefits of Tamarillo fruits
Selection. Tamarillo season begins in New Zealand from May until October. Choose welldeveloped, bright, uniform colored, ripe and ready to eat fruits. Tamarillos available in several attractive colors of orange, goldenyellow, deep red, maroon, etc. Look for hea .....
Benefits of Kiwi Fruits
Season. Kiwi fruits are available on the market from April through December, but are most abundant from June to October. The taste of kiwi fruits is similar to a mixture of bananas, pineapples and strawberries, and is an excellent source of vitamins and mine .....
Innovative Products Ideas
Modified hand cart with steering and brakes. The idea is to incorporate easy steering mechanism and brakes to make turning hand carts easy and arrest slide on inclines. Young Usman saw a street vendor struggling with his hand cart while negotiating a turn on an incline, which triggering this id .....
Luxurious Hospitals Most Patients Would Kill To Die In
Fortis La Femme Hospital India. Fortis La Femme Hospital is India s pride and is considered the best and richest hospital in the country. The presidential suite is one of the most expensive hospital rooms in the whole world. .....
Important Tips for Hiring the Best Employees
Excused Absence Definition. The scheduled or unscheduled time off from work that occurs when an employee is not present at work during a normally scheduled work period is called an absence. An excused absence is an absence that the employee schedules in advance with his or her .....
Tips for Perfect Reception Party
Show Appreciation. Make sure youve designated someone, such as the best man, to distribute gratuity envelopes youve prepared at party end. you will need to tip all service providers, including the catering and reception staff (unless gratuity is added to the total bill .....
Ajanta Caves
Cave Two. Cave 2, adjacent to Cave 1, is known for the paintings that have been preserved on its walls, ceilings, and pillars. It looks similar to Cave 1 and is in a better state of preservation.Cave 2 has a porch quite different from Cave one. Even the fa .....
Benefits of Durian
Improves the general wellbeing. Durian consists of higher quantities of amino acids particularly tryptophan. This is particularly recognized to relieve signs and symptoms of sleeplessness, depression and anxiety. It may also help in increasing the amount of serotonin perfectly loca .....
Most Famous Landmarks Around the World
Easter Island in the Polynesian Triangle Pacific Ocean. Easter Island is a Chilean island in the southeastern Pacific Ocean, at the southeasternmost point of the Polynesian Triangle. Easter Island is famous for its 887 extant monumental statues, called moai, created by the early Rapa Nui people. In 1995, .....
Fitness Tips
Ramp it up slowly. If you hate exercise or have a challenge with time getting it on your schedule make incremental changes each week. Aim for 20 minute workouts at first. Or start with walking. Build upon your healthy habits each week adding more time to your workouts .....
Benefits of Cassava
Cassava is classified as sweet or bitter. Cassava is classified as sweet or bitter. Farmers often prefer the bitter varieties because they deter pests, animals, and thieves. Like other roots and tubers, both bitter and sweet varieties of cassava contain antinutritional factors and toxins. It .....
Most Powerful Cities On Earth
New York. It may come as no surprise that the Big Apple, New York City, tops our list as the worlds most financially powerful city. Wall Street and the rest of the major financial institutions bring NYCs total economic output to $1.4 trillion. .....
Famous Indian Scientists
Brahmagupta. Brahmaguptawas an Indian mathematician and astronomer who wrote two important works on Mathematics and Astronomy: the Br?hmasphu?asiddh?nta (Extensive Treatise of Brahma) (628), a theoretical treatise, and the Kha??akh?dyaka, a more practical text Th .....
What to Eat in Haryana
Amla Chutney. A super simple and super healthy chutney recipe which i tried at home and i kept it in haryanvi chutney recipes because i got an idea to prepare amla chutney after seeing the experiments done for chutneys in haryanvi kitchens.Amla chutney just turned .....
Benefits of Mint Leaf
On the other hand. At work or at home mint rubbing is an excellent choice for spending quality time and for leaving worries and problems behind. Mint rubbing belongs to a larger group of time management techniques that includes gas burning, pulling the cats tail, cutti .....
Benefits of Rambutan fruits
Very rich in iron. Rambutan is very rich in iron, which is needed to control the oxygen levels in the body. Iron helps prevent fatigue and dizziness caused by anemia. In addition, meat rambutan also meet 4.3 percent of the daily phosphorus needs for the body. Phosphoru .....
Myth about Aging
Older women are less successful in new pursuits. Some of the best and brightest women, though past the half century mark in years, are still climbing the ladder of success in the world . .....
Small Things That Can Bring You Joy
Read a Novel. Letting your mind escape into a fantasy realm for awhile can actually boost your happiness. So open up a good book and don t be afraid to let your imagination run away with it. .....
Most Stylish Athletes
Joe Namath. Having Manhattan as a platform can transform the most scruffy athlete into a style icon. The New York Jets quarterback sported long hair, the occasional full length fur and a flamboyance that did not seem the least bit studied. While the man certainl .....
Beautiful Punjabi Mehndi Designs
Bling. If you are planning to go big on your wedding mehndi, you can find ways of adding glimmer to your Punjabi bridal mehndi designs. Though the glitters will go away after a few washes, they are certainly worth it on your big day! .....
Romantic Valentines Day Ideas
Dedicate a day. Dedicate a day to the one you love plan a day filled with his favorite things. .....
Cutest and Pretty Dogs
Raggedy Eared Pom Pom. This itty-bitty pooch is big on hairand love. .....
Tips To Prepare a Government Job Interview
Find out How Many Other Candidates Are Appearing for the Interview. Ascertaining competition will give you an idea about the interview. If the numbers of candidates are more, then Interview would going to be tough. .....
The Most Difficult Languages To Learn In The World
Albanian. An IndioEuropean language spoken by the people of Kosovo, Alabania, Bulgaria and the Republic of Macedonia, the Albanian language is a centuriesold language that was first spoken by the old communities of Montenegro, Italy and Greece. It shares lexic .....
Most Beautiful Mosques In The World
THE LONDON CENTRAL MOSQUE LONDON. Located in Regent .....
Famous Indian Scientists
Arun Netravali. Arun N Netravali (born 26 May 1946 in Mumbai, India) is an IndianAmerican computer engineer who has contribution in digital technology including HDTV He conducted seminal research in digital compression, signal processing and other fields Netravali w .....
Benefits of Elderberry
It also cures infections. It also cures infections, diabetes, rheumatism, inflammatory diseases and neuralgia.Elderberry can act as a laxative, as a medicine to cure skin disorders, can aid in weight loss and as a diuretic. This shrub typically grows to approximately ten fee .....
Rose Day
Rose Day Wallpapers. I love you have you here, hope you enjoyed happy rose day wallpapers 2015, rose day wallpaper or happy rose day wallpaper. .....
Rules to play Foosball
Flip a coin. A coin flip decides who serves the foosball to start the foosball game. After the first goal is scored, the rule is that the team who was last scored on gets to serve the next ball. This rule keeps the game fair for both opponents. The foosball must .....
Reasons You Should Brush Your Teeth
Delayed Conception. As bad as it is to have your own body attacked by bacteria, if you are an expectant mother, there is another body that you should be concerned about. The bacterial infection can actually be passed to your child and cause problems with delivery. Not o .....
Ebola Virus
Transmission from person to person. Infected people typically dont become contagious until they develop symptoms. Family members are often infected as they care for sick relatives or prepare the dead for burial.Medical personnel can be infected if they dont use protective gear, such as .....
Road Safety
Cyclists Be cautious. Stop before entering a moving traffic, especialy from merging traffic, parking lot. Be cautious in such conditons since the traffic is free flowing and may cause accidents if we r negligent. .....
Parachute Activity
Mousetrap. Kids stand around parachute and hold it high above their heads (a very taut parachute is needed so have the kids take an extra step or two backwards). Number off the kids. When a number is called, those students become the mice. They must crawl under .....
Rules to play Roller Skating
Scoring. Points are scored as follows A jammer receives one point for every member of the opposing team he or she passes, every time he or she laps the pack. If a blocker commits a foul on a jam skater, the jam skater will be awarded the point that he or she .....
Business Success Tips
Assess your HR needs. Do your employees have the skills your business needs to grow in 2013? Whether you need to provide additional training, hire new employees or outsource to independent contractors, think about how you will fill the gaps. .....
Benefits of Cloves
Diabetes. Along with blood purification, clove oil helps control the level of blood sugar, making it very useful to patients suffering from diabetes. This is primarily due to the phenol concentration found in clove oil, which is one of the highest in terms of .....
Benefits of Hair Straightening
Heat damage to your hair is hard to repair. Many people do not realize that even the highest quality professional ceramic and tourmaline flat irons can have a damaging effect on your hair if used incorrectly or too frequently, or if your hair is not adequately protected. Heat damage to your ha .....
Watches You Cant Stop Watching
Issey Miyake Silap003 Twelve Mens Watch. Another simple design for those of us who know our way around a clock face otherwise don t spend Dollar 400 on a Watch that s going to impress your friends but challenge you every time you want to know the time. .....
Greatest Technological Inventions of the Past 25 Years
Caller ID. Many of you probably can t fathom a time when you had to answer the phone without knowing who was on the other line, but before 1988 that s the way it was. After a Brazilian inventor wasn t able to secure a patent, Bell Laboratories, AT&T, and Wester .....
Coolest New Businesses In America
The Green Microgym. Its not really surprising to find a Portland gym where your exercise actually creates energy to power the building. Founder Adam Boesel worked through many prototypes before making those which plug .....
Bodyweight Exercises
Tuck Jump. Standing with the knees slightly bent, jump up as high as possible (pretend Jeremy Lin is watching. ) and bring the knees in toward the chest while extending the arms straight out. Land with the knees slightly bent and quickly jump (on it) again. .....
Munshi Premchand
Biography. Born July 31, 1880 Died October 8, 1936.Achievements Premchand brought realism to Hindi literature. Premchand wrote on the realistic issues of the day communalism, corruption, zamindari, debt, poverty, colonialism etc. He avoided the use of highly Sa .....
Best Names at the Sochi Olympics
Jakov Fak. Jakov Fak the biathlon skier representing Slovenia was born on august 1st 1987 in Croatia. He started his career in 2001 and participated in a number of world championships at the junior level. He won bronze in his first major world championships in .....
Fastest Vehicles Known To The Human Race
Steam train. Top speed of 125.88 mph (202.58 km/h) for a train might not seem as astonishing these days but considering this speed was achieved in 1938 by a steam locomotive (4468 Mallard), the record absolutely deserves to be on the list. .....
Most Attractive People in Sports
Ana Ivanovic Serbian Tennis Player. Tennis is a sport that does more than its best to not stand in the way of a womans appeal; it enhances it. Skimpy outfits that tend to flutter around the butt region? Check. Just enough sweat to look like a scene in a beer commercial? Check. Um...gr .....
Strangely Unique Schools
Play Mountain Place. Play Mountain Place is a child centered, humanistic, progressive, alternative, experiential, play based preschool and elementary school located in Los Angeles. For over sixty five years, children have been encouraged to discover the joys of learning .....
Christmas Poems
The Three Kings. Three Kings came riding from far away, Melchior and Gaspar and Baltasar; Three Wise Men out of the East were they, And they travelled by night and they slept by day, For their guide was a beautiful, wonderful star. The star was so beautiful, large, .....
Benefits of Pineapple
Pineapple is filling. Nutrition Facts.com rates pineapples fullness factor at 3.3 on a 5.0 scale. Those who are looking for a sweet snack can fill up on pineapple and consume relatively few calories compared to highsugar or highfat foods such as potato chips and bread. Di .....
SuperFood
Limes. Limes are sweeter than lemons and they also contain more citric acid, a compound essential to the metabolic process that burns carbohydrates, proteins, and fats to turn them into water and carbon dioxide and release energy in the body. Like lemons, l .....
Rules to play Roller Skating
The Diamond. A similar tactic, wherein four blockers form a rough diamond around the opposing jammer to prevent her from getting through the pack. .....
President Of India
Sarvepalli Radhakrishnan. Period-13-May-1962 to 13-May-1967 Political party-Independent Born: September 5, 1888 Died: April 17, 1975 Achievements: First Vice President and second President of India. Placed Indian philosophy on world map. Sarvepalli Radhakrishnan was firs .....
Precautions while using CNG
Depressurizing CNG Systems. 1. Ensure that the vehicle is turned off. 2. Turn all cylinder shutoff valves one on each cylinder clockwise to the OFF CLOSED position. 3. Ensure that the manual shut off valve is in the ON OPEN position. 4. Turn on the vehicle and run the engine un .....
Most Famous Landmarks Around the World
Christ the Redeemer in Rio de Janeiro. Christ the Redeemer is an Art Deco statue of Jesus Christ in Rio de Janeiro, Brazil, created by French sculptor Paul Landowski and built by the Brazilian engineer Heitor da Silva Costa, in collaboration with the French engineer Albert Caquot. .....
Benefits of Jalapeno
plant food. Plant foods such as jalapenos, contain different phytonutrients, or plant nutrients, which are beneficial for your health. Carotenoids called lutein and zeaxanthin are two nutrients found in jalapenos. These compounds are deposited in the retina of y .....
Management Tips
Set Goals. Your team must know what is expected of them, and what will make them stand out amongst others. Each member of the team must be given clear measurable goals. Discuss and agree with each member before making it formal, your team member must accept it .....
Rules to play Surfing
Legal Disclaimers. All participants agree to abide by the terms of these official rules and the Legal Disclaimers below, and by the decisions of Fantasysurfer.com, which are final and binding on all matters pertaining to the game. .....
Know World Carnival
Happy New Year. January 1 represents the fresh start of a new year after a period of remembrance of the passing year, including on radio, television and in newspapers, which starts in early December in countries around the world. The celebration on the last day of y .....
Tatoo Designs
Phoenix Tattoos. The phoenix is a symbol of death and rebirth as the ashes of the burnt phoenix bring it back to life, and a new being is created.It is a good symbol for you if you have been going through some hard times that have transformed you. .....
Brics
4th BRIC summit India. The 2012 BRICS summit was the fourth annual BRICS summit, an international relations conference attended by the heads of state or heads of government of the five member states Brazil, Russia, India, China and South Africa. The summit was held at Taj .....
Chourishi Systems