Electricity Basics
What is electricity?
Electricity is a general term of a variety of phenomena resulting from the presence and flow of electric charge. Electricity is actually a secondary energy source, also referred to as an energy carrier. That means that we get electricity from the conversion of other sources of energy, such as coal, nuclear, or solar energy. These are called primary sources. The energy sources we use to make electricity can be renewable or non-renewable, but electricity itself is neither renewable or nonrenewable.
Electricity is an energy fueled by the transfer of electrons from positive and negative points within a conductor.
All things are made out of atoms, and electrons are part of the atom. Atom may lose or gain an electron when protons and electrons are not balance, then the free electrons movement makes electric current.
How is electricity generated?
Electric generator is a device that converts mechanical energy to electrical energy. This generator forces electric charge to flow through an external electrical circuit. This whole process is based on magnetism and electricity relationship. When a wire moves across a magnetic field, the electric current will occur in the wire. The large generators used by the electric utility industry have a stationary conductor. A magnet attached to the end of the shaft is positioned in a stationary conducting ring that is wrapped with a long, continuous piece of wire. When the magnet rotates, it induces a small electric current in each section of wire as it passes. Each section of wire constitutes a small, separate electric conductor. All the small currents of individual sections add up to one current of considerable size. This current is what is used for electric power.
There are many electrical machines used by power plants, such as turbines, engines, water wheels and etc. Those are the machines that will drive an electric generator or a device that will convert mechanical or chemical energy to electricity. The most common methods to generate electricity according to the utility used are steam turbines, internal-combustion engines, gas combustion turbines, water turbines and wind turbines.
Turbine converts the kinetic energy of a moving fluid (liquid or gas) to mechanical energy. Steam turbines have a series of blades mounted on a shaft against which steam is forced, thus rotating the shaft connected to the generator.
How is electricity delivered to your home?
Flip a switch and the darkness disappear. Adjust a thermostat and cool air pours into a room. Electricity makes these miracles possible. But do you wonder how electricity gets to your home?
The electricity produced by a generator travels along cables to a transformer, which changes electricity from low voltage to high voltage. Transformer is a device that can change electricity from low to high voltage. Transformers are needed to allow electricity can be moved long distance more efficiently. Transmission lines are used to carry the electricity to substations. These substations have transformers that do the opposite from the first one. It changes the high voltage electricity to a lower one. From the substations electricity will be distributed to homes, office and factories.
How is electricity measured?
Electricity makes our lives easier, but it can seem like a mysterious force. Measuring electricity is confusing because we cannot see it. We are familiar with terms such as watt, volt, and amp, but we may not have a clear understanding of these terms. We buy a 60-watt light bulb, a tool that needs 120 volts, or a vacuum cleaner that uses 8.8 amps, and we don't think about what those units mean.
Again, using the flow of water as an analogy can make electricity easier to understand. The flow of electrons in a circuit is similar to water flowing through a hose. If you could look into a hose at a given point, you would see a certain amount of water passing that point each second.
The amount of water depends on how much pressure is being applied—how hard the water is being pushed. It also depends on the diameter of the hose. The harder the pressure and the larger the diameter of the hose, the more water passes each second. The flow of electrons through a wire depends on the electrical pressure pushing the electrons and on the cross-sectional area of the wire.
Ampere – A
Ampere the SI unit of electric current in practical terms, the ampere is a measure of the amount ofelectric charge passing a point in an electric circuit.
Electric current is the same as electric quantity in movement, or quantity per unit time, expressed like
I = q / t
Note:
I = electric current (ampere)
q = electric quantity (coulomb)
t = time (s)
Ohm - Ω
Ohm is derived SI unit of electrical resistance - the resistance between two points on a conductor when a constant potential difference of 1 volt between them produces a current of 1 ampere.
Volt - V
The Volt - V - is the Standard International unit of electric potential or electromotive force. A potential of one volt appears across a resistance of one ohm when a current of one ampere flows through that resistance.
Reduced to SI base units,
1 (V) = 1 (kg m2 / s3 A)
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References
1. Woodford, Chris. "Electricity." January 29, 2012. <http://www.explainthatstuff.com/electricity.html>
2. "Electricity Basics." Pasific Gas and Electric Energy. <http://www.pge.com/microsite/safety_esw_ngsw/esw/science/basics.html>
Acknowledgements
1. "Image: Electricity Delivery." Visual Photos. <http://www.srpnet.com/education/electdelivery.aspx>
2. "Image: Generator." <http://www.bizaims.com/files/generator.JPG>
3. "Image: 2003 Commercial Building Energy Consumption Survey.: U.S. Energy Information (September 2008)
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