The Magic Of Electricity by. Tory Blume : The Magic Of Electricity by. Tory Blume
Electricity: A form of energy associated with a flow of electrons whose movements can create fields of force and generate energy : Electricity: A form of energy associated with a flow of electrons whose movements can create fields of force and generate energy Electricity is a form of energy. It is generated by millions of free-flowing electrons whose movements create force fields and generate energy from motion. When you do things like surf the Net, heat something in the microwave, watch TV, and turn on the light in your bedroom, you are using electricity.
If you want to understand electricity, you first need to know a little about matter, atoms, and electrons. Matter is anything that takes up space or has mass. Everything you can touch is made of matter. Atoms are the very small "building blocks" of matter. Everything you touch is matter and is made up of atoms (lots and lots of atoms!). These very small atoms are made up of an even smaller nucleus and one or more small electrons circling the nucleus. Electrons always have a negative ("-") electric charge, and it is this electric charge that is responsible for what we call electricity.
Did You Know? Electrons don't really race from one end of the wire to the other like sprinters at a track meet. In an electric current the electrons jump from one atom to another, pushing other electrons in front of them as they go. They really behave more like runners in a relay race, passing along the baton (electrical energy) from one atom to the next. The electrons don't actually travel very fast, but the electrical energy that they create travels at the speed of light! Remember that electrons carry a negative electrical charge. When electrons move from one place to another they take that negative charge with them. It is this movement of charge that we refer to as electricity! So if you can get a bunch of electrons to cooperate and all head in the same direction, you've got electricity! ELECTRICITY AT WORK
If you walk across a carpet, electrons move from the rug to you. Now you have extra electrons. Touch a door knob and ZAP! The electrons move from you to the knob. You get a shock. : If you walk across a carpet, electrons move from the rug to you. Now you have extra electrons. Touch a door knob and ZAP! The electrons move from you to the knob. You get a shock. Static electricity is usually caused when certain materials are rubbed against each other, like wool on plastic or the soles of your shoes on the carpet. The process causes electrons to be pulled from the surface of one material and relocated on the surface of the other material. Rubbing a balloon on a wool sweater creates charges on the surfaces. The same goes for a balloon and a wall. The material that loses electrons ends up with an excess of positive (+) charges. The material that gains electrons ends up an excess of negative (-) charges on its surface. STATIC ELECTRICITY
ELECTRICITY ON THE MOVE : ELECTRICITY ON THE MOVE In the diagram to the left there has to be a complete electric circuit to light this bulb. The electric current flows from one terminal of the battery through the wire to the other terminal. If we make a gap or a break in the circuit by using a switch, the electricity cannot flow through and the light goes out. Air is an insulator. When we flip the switch on, the two metal parts in the switch come together to close the gap and complete the electrical circuit. In this electrical circuit below the electrical current flows from one terminal through a metallic plate that is highly conductive, a switch and a fuse to complete the electrical circuit. If there is a break or gap in any of these the circuit will not be complete and the light will not illuminate. A fuse is a safety device that breaks the circuit if to much electricity is passing through it.
ELECTRICITY KILLS : ELECTRICITY KILLS An electric shock can occur upon contact of a human or animal body with any source of voltage high enough to cause sufficient current flow through the muscles or nerves. The minimum detectable current in humans is thought to be about 1 mA. The current may cause tissue damage or heart fibrillation if it is sufficiently high. When (and only when) an electric shock is fatal, it is called electrocution.
The average lightning bolt carries about 30,000 amps of charge, has 100 million volts of electric potential, and is about 50,000｡F.
SAFETY : SAFETY Microshock is a direct current path to the heart tissue
Macroshock is current flowing across intact skin and through the body. Current traveling from arm to arm or between an arm and a foot is likely to traverse the heart and so is much more dangerous than current traveling between a leg and the ground. Avoid contact of any kind with power lines either downed in a storm or ones that are leading into a home. They may cause serious injury or even death by electrocution. Never overload electrical outlets and circuits. Overloaded electrical outlets, or circuits that supply power to several outlets, is a major cause of residential fires. Overloaded outlets and circuits carry too much electricity, which generates heat in undetectable amounts. The heat causes wear on the internal wiring system and can ignite a fire. The term "ground" refers to a conductive body, usually the earth. "Grounding" a tool or electrical system means intentionally creating a low-resistance path to the earth. When properly done, current from a short or from lightning follows this path, thus preventing the buildup of voltages that would otherwise result in electrical shock, injury and even death. When you create that path to ground is when shock or electrocution occurs.
Ground fault circuit interrupter (GFCI) are good idea when plugging devices such as a tv’s, toaster, and or tools into walls.
FATHERS OF ELECTRICITY : FATHERS OF ELECTRICITY Ben Franklin an American writer, publisher, scientist and diplomat, who helped to draw up the US Constitution also helped to discover the magic of electricity. Franklin started working with electricity in the 1740's and believed that lightning was a flow of electricity taking place in nature. In 1752 Franklin proved this theory that lightning was a form of electrical energy by fastening a iron spike to a silken kite, which he flew during a thunderstorm, while holding the end of the kite string by an iron key. When lightening flashed, a tiny spark jumped from the key to his wrist. The experiment proved Franklin’s theory, but was extremely dangerous- He could easily have been killed.
ELECTRIC LIGHT : ELECTRIC LIGHT When an electric current passes through a wire, the atoms not only produce heat when they resist the movement of electrons, they may also change some of the electrical energy into light. In 1878 Joseph Swan, a British scientist, invented the incandescent filament lamp and within twelve months Thomas Edison made a similar discovery in America. Light bulbs contain very thin wires, called filaments, which force the electrons to travel through an extremely small area. The resistance is further increased by making the wire very long and coiling it up to fit into a small space. The wire resists the current so much that the filament becomes hot enough to glow white. Swan and Edison later set up a joint company to produce the first practical filament lamp. Prior to this, electric lighting had been by crude arc lamps. Edison used his DC generator to provide electricity to light his laboratory and later to illuminate the first New York street to be lit by electric lamps, in September 1882. Edison's successes were not without controversy, however although he was convinced of the merits of DC for generating electricity, other scientists in Europe and America recognized that DC brought major disadvantages.
Michael Faraday : Michael Faraday The credit for generating electric current on a practical scale goes to the famous English scientist, Michael Faraday. Faraday was greatly interested in the invention of the electromagnet, but his brilliant mind took earlier experiments still further. If electricity could produce magnetism, why couldn't magnetism produce electricity. In 1831, Faraday found the solution. Electricity could be produced through magnetism by motion. He discovered that when a magnet was moved inside a coil of copper wire, a tiny electric current flows through the wire. Of course, by today's standards, Faraday's electric dynamo or electric generator was crude, and provided only a small electric current be he discovered the first method of generating electricity by means of motion in a magnetic field.
Nearly 40 years went by before a really practical DC (Direct Current) generator was built by Thomas Edison in America.
James Watt : James Watt James Watt When Edison's generator was coupled with Watt's steam engine, large scale electricity generation became a practical proposition. James Watt, the Scottish inventor of the steam condensing engine, was born in 1736. His improvements to steam engines were patented over a period of 15 years, starting in 1769 and his name was given to the electric unit of power, the Watt.Watt's engines used the reciprocating piston, however, today's thermal power stations use steam turbines, following the Rankine cycle, worked out by another famous Scottish engineer, William J.M Rankine, in 1859.
A steam engine is an external combustion heat engine that makes use of the thermal energy that exists in steam, converting it to mechanical work. Steam engines were used as the prime mover in pumps, locomotives, steam ships and steam tractors, and were essential to the Industrial Revolution. They are still widely used, particularly for electrical power generation using the steam turbine. A steam engine requires a boiler to boil water to produce steam. The expansionﾑor contractionﾑof steam exerts force upon a piston or turbine blade, whose motion can be harnessed for the work of turning wheels or driving other machinery. One of the advantages of the steam engine is that any heat source can be used to raise steam in the boiler; but the most common is a fire fueled by wood, coal or oil or the utilization of the heat energy generated in a nuclear reactor.
Slide11 : A power generation plant is a facility designed to produce electric energy from another form of energy, such as: Heat (thermal) energy generated from Fossil Fuels, such as coal◦ petroleum◦ and natural gas. Others include solar Thermal energy, Geothermal energy and Nuclear energy. Potential energy from falling water in a hydroelectric facility, is another form of power generation as well as Wind energy and Solar Electric from solar (photovoltaic) cells and Chemical energy from fuel cells, and batteries. There are many different types of electric power generating plants. The major types generating electric power today are shown below. Nuclear Power Plant (Above)
Hydroelectric Power Plant (Right) Fossil Fuel Power Plant (Left)
Solar Thermal Power Plant (Below) Wind Power Towers (Left)
Geothermal Power Plant (Below)
Power Transmission : Power Transmission 1 ) Power station generators make electricity at 11000 to 25000 volts. To deliver electricity with as little waste as possible a very high voltage must be used. So transformers at the transmission sub-station step up the voltage up to 765,000 volts.
2 ) Electricity can be carried over the countryside on overhead lines or underground cables. Pylons over the ground are ugly but they are much cheaper to make and erect than underground cables as you can see.
3 ) To avoid power cuts caused by lightning, electricity supply lines are arranged in an inter-connecting grid. If one of the supplies to a factory is cut off, it can still get its supply from another line.
4 ) When the electricity reaches the second of the two main substations, it is still at a very high voltage. Step-down transformers in the substation reduce the voltage to a lower level which is carried on smaller, lighter pylons.
5 ) The final link in the chain from power stations to commercial and residential facilities is the transmission of the stepped-down voltage.
Alternating Current : Alternating Current Alternating current is useful because its voltage can be changed by using a transformer, which is simply two coils of insulated wire wound round an iron core. Although there is no electrical connection between the two coils, any voltage in the first coil sets up a voltage in the second coil. This effect is called induction. Larger or smaller voltages, whatever is needed can be set up by varying the number of turns in the two coils. Of the two forms of electricity, power stations use alternating current. To make alternating current, powers stations use generators that have coils like an electric motor. As each coil is turned between the two magnets, current is made the exact opposite of an electric motor. But the amount of current varies as the coil turns round. The picture above shows you how the amount of current varies as the coil turns. The turning coil is shown on the top of the picture. You can see that when the coil is upright, no current is made at all. As it turns the current flow begins to increase, but soon the flow gets smaller again. After the coil has turned half a circle, the current starts to flow the other way. Power stations produce 50 of these two-way cycles every second.
21st Century Electricity : 21st Century Electricity If we go on using coal, oil and gas as fast as we do now, they could be used up in under 100 years. So scientists are looking for other ways of producing electricity. If you want to help these scientist, tell your friends what you have learned and grow to love and understand the magic of electricity even more.