With enough outside force, a valence electron can escape orbit of the atom and become free. Free electrons allow us to move charge, which is what electricity is all about. Speaking of charge As we mentioned at the beginning of this tutorial, electricity is defined as the flow of electric charge. Charge is a property of matter--just like mass, volume, or density.
It is measurable. Just as you can quantify how much mass something has, you can measure how much charge it has. In order to move charge we need charge carriers , and that's where our knowledge of atomic particles--specifically electrons and protons--comes in handy. Electrons always carry a negative charge, while protons are always positively charged.
Neutrons true to their name are neutral, they have no charge. Both electrons and protons carry the same amount of charge, just a different type. A lithium atom 3 protons model with the charges labeled. The charge of electrons and protons is important, because it provides us the means to exert a force on them. Electrostatic force! Electrostatic force also called Coulomb's law is a force that operates between charges.
It states that charges of the same type repel each other, while charges of opposite types are attracted together. Opposites attract, and likes repel. The amount of force acting on two charges depends on how far they are from each other. The closer two charges get, the greater the force either pushing together, or pulling away becomes.
Thanks to electrostatic force, electrons will push away other electrons and be attracted to protons. This force is part of the "glue" that holds atoms together, but it's also the tool we need to make electrons and charges flow!
We now have all the tools to make charges flow. Electrons in atoms can act as our charge carrier , because every electron carries a negative charge. If we can free an electron from an atom and force it to move, we can create electricity. Consider the atomic model of a copper atom, one of the preferred elemental sources for charge flow. In its balanced state, copper has 29 protons in its nucleus and an equal number of electrons orbiting around it. Electrons orbit at varying distances from the nucleus of the atom.
Electrons closer to the nucleus feel a much stronger attraction to the center than those in distant orbits. The outermost electrons of an atom are called the valence electrons , these require the least amount of force to be freed from an atom. This is a copper atom diagram: 29 protons in the nucleus, surrounded by bands of circling electrons.
Electrons closer to the nucleus are hard to remove while the valence outer ring electron requires relatively little energy to be ejected from the atom. Using enough electrostatic force on the valence electron--either pushing it with another negative charge or attracting it with a positive charge--we can eject the electron from orbit around the atom creating a free electron.
Now consider a copper wire: matter filled with countless copper atoms. As our free electron is floating in a space between atoms, it's pulled and prodded by surrounding charges in that space. In this chaos the free electron eventually finds a new atom to latch on to; in doing so, the negative charge of that electron ejects another valence electron from the atom. Now a new electron is drifting through free space looking to do the same thing. This chain effect can continue on and on to create a flow of electrons called electric current.
A very simplified model of charges flowing through atoms to make current. Some elemental types of atoms are better than others at releasing their electrons. To get the best possible electron flow we want to use atoms which don't hold very tightly to their valence electrons.
An element's conductivity measures how tightly bound an electron is to an atom. Elements with high conductivity, which have very mobile electrons, are called conductors. These are the types of materials we want to use to make wires and other components which aid in electron flow. Metals like copper, silver, and gold are usually our top choices for good conductors. Elements with low conductivity are called insulators. Insulators serve a very important purpose: they prevent the flow of electrons.
Popular insulators include glass, rubber, plastic, and air. Before we get much further, let's discuss the two forms electricity can take: static or current. In working with electronics, current electricity will be much more common, but static electricity is important to understand as well.
Static electricity exists when there is a build-up of opposite charges on objects separated by an insulator. Static as in "at rest" electricity exists until the two groups of opposite charges can find a path between each other to balance the system out. When the charges do find a means of equalizing, a static discharge occurs.
The attraction of the charges becomes so great that they can flow through even the best of insulators air, glass, plastic, rubber, etc. Static discharges can be harmful depending on what medium the charges travel through and to what surfaces the charges are transferring. Charges equalizing through an air gap can result in a visible shock as the traveling electrons collide with electrons in the air, which become excited and release energy in the form of light.
Spark gap igniters are used to create a controlled static discharge. Opposite charges build up on each of the conductors until their attraction is so great charges can flow through the air. One of the most dramatic examples of static discharge is lightning. When a cloud system gathers enough charge relative to either another group of clouds or the earth's ground, the charges will try to equalize.
As the cloud discharges, massive quantities of positive or sometimes negative charges run through the air from ground to cloud causing the visible effect we're all familiar with. Static electricity also familiarly exists when we rub balloons on our head to make our hair stand up, or when we shuffle on the floor with fuzzy slippers and shock the family cat accidentally, of course.
In each case, friction from rubbing different types of materials transfers electrons. The object losing electrons becomes positively charged, while the object gaining electrons becomes negatively charged. The two objects become attracted to each other until they can find a way to equalize. Working with electronics, we generally don't have to deal with static electricity.
When we do, we're usually trying to protect our sensitive electronic components from being subjected to a static discharge. Preventative measures against static electricity include wearing ESD electrostatic discharge wrist straps, or adding special components in circuits to protect against very high spikes of charge. Current electricity is the form of electricity which makes all of our electronic gizmos possible. This form of electricity exists when charges are able to constantly flow.
As opposed to static electricity where charges gather and remain at rest, current electricity is dynamic, charges are always on the move.
We'll be focusing on this form of electricity throughout the rest of the tutorial. In order to flow, current electricity requires a circuit : a closed, never-ending loop of conductive material.
A circuit could be as simple as a conductive wire connected end-to-end, but useful circuits usually contain a mix of wire and other components which control the flow of electricity.
The only rule when it comes to making circuits is they can't have any insulating gaps in them. If you have a wire full of copper atoms and want to induce a flow of electrons through it, all free electrons need somewhere to flow in the same general direction. Copper is a great conductor, perfect for making charges flow.
If a circuit of copper wire is broken, the charges can't flow through the air, which will also prevent any of the charges toward the middle from going anywhere. On the other hand, if the wire were connected end-to-end, the electrons all have a neighboring atom and can all flow in the same general direction. We now understand how electrons can flow, but how do we get them flowing in the first place? Then, once the electrons are flowing, how do they produce the energy required to illuminate light bulbs or spin motors?
For that, we need to understand electric fields. We have a handle on how electrons flow through matter to create electricity. That's all there is to electricity. Well, almost all. Now we need a source to induce the flow of electrons. Most often that source of electron flow will come from an electric field. A field is a tool we use to model physical interactions which don't involve any observable contact. Fields can't be seen as they don't have a physical appearance, but the effect they have is very real.
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Also in Coal explained Coal Mining and transportation Where our coal comes from Imports and exports How much coal is left Use of coal Prices and outlook Coal and the environment. Wind power is derived from the conversion of the energy contained in wind into electricity.
Wind power, like the sun, is usually an expensive source of producing electricity. In , It was used for roughly 4. A wind turbine is similar to a typical wind mill.
Biomass wood, municipal solid waste garbage , and agricultural waste, such as corn cobs and wheat straw, are some other energy sources for producing electricity. These sources replace fossil fuels in the boiler. The combustion of wood and waste creates steam that is typically used in conventional steam-electric plants. In , biomass accounts for 1.
The electricity produced by a generator travels along cables to a transformer, which changes electricity from low voltage to high voltage. Electricity can be moved long distances more efficiently using high voltage.
Transmission lines are used to carry the electricity to a substation. Substations have transformers that change the high voltage electricity into lower voltage electricity. From the substation, distribution lines carry the electricity to homes, offices and factories, which require low voltage electricity. Electricity is measured in units of power called watts.
It was named to honor James Watt , the inventor of the steam engine. One watt is a very small amount of power. It would require nearly watts to equal one horsepower. A kilowatt represents 1, watts. A kilowatt-hour kWh is equal to the energy of 1, watts working for one hour. The amount of electricity a power plant generates or a customer uses over a period of time is measured in kilowatt-hours kWh.
Kilowatt-hours are determined by multiplying the number of kW's required by the number of hours of use. For example, if you use a watt light bulb 5 hours a day, you have used watts of power, or. Actively scan device characteristics for identification. Use precise geolocation data. Select personalised content.
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