Electricity

Electricity is the set of physical phenomena associated with the presence and motion of matter that has a property of electric charge. Electricity is related to magnetism, both being part of the phenomenon of electromagnetism. Various common phenomena are related to electricity, including lightning, static electricity, electric heating, electric discharges and many others.

The presence of an electric charge, which can be either positive or negative, produces an electric field. The movement of electric charges is an electric current and produces a magnetic field. When a charge is placed in a location with a non-zero electric field, a force will act on it. If the charge moves, the electric field would be doing work on the electric charge. Thus we can speak of electric potential at a certain point in space, which is equal to the work done by an external agent in carrying a unit of positive charge from an arbitrarily chosen reference point to that point without any acceleration and is typically measured in volts.

Electric power where electric current is used to energise equipment; Electronics which deals with electrical circuits that involve active electrical components such as vacuum tubes, transistors, diodes and integrated circuits, and associated passive interconnection technologies.

Theory and Uses

Electricity is a really fast way to transfer energy. Energetics can be used to generate electricity and because electricity travels really fast, it is so far the best way to transfer energy. Electric charge is caused by any atom that has a charge imbalance. This is caused through many means but will be discussed more in the Chemistry page. Once you have a charge imbalance, it will be attracted to the opposite type of charge. Positive will be attracted to negative and vice versa. You can harness this by creating or using a substance that has an easy path for this charge to flow through. These materials are called conductors, and the opposite of a conductor is called an insulator. Insulators have a really high resistance to flow of electric charge. Resistance is the term that is used to describe blocks in the electricity's path. Similar to water in a river, the more rocks and stuff are in the river, the more it has to bounce around and thus the slower the average current of the river is. The same is true for electricity. The thinner the conductor, or the less it is able to conduct, the higher the resistance becomes and the lower the current becomes. We can use this charge through a conductor to carry energy. The best conductor to expense ratio we have found is in a material called copper. That is the material you will see in wires all around you.

There are multiple methods of producing current. The first was to use triboelectricity, the phenomenon where rubbing things (such as glass and paper) produces a high voltage at low current. The second was to use influence machines, which use electrostatic induction. When a charged object is brought near another, the other object's electrons get pushed or pulled from the object. An example of an influence machine is a Wimshurst generator. Both of these methods produce high voltage at low current. Using a galvanic cell, where two different metals are placed in an electrolyte, it is possible to provide low voltage at higher current. One can also use Lorentz forces to generate electricity. Spinning a disk with a magnetic field going through its surface will create a voltage across the center and outside, which can be extracted. Lastly, electric fields can be generated by changing magnetic fields, and be captured more efficiently using coils of wire, sometimes with ferromagnetic materials (like iron) inside.

Storing electrical energy can be done with an inductor or capacitor. A capacitor can be made with a dielectric, like glass, paper, or air, and two sheets of metal. The sheets must not be electrically connected to each other, and they need to be placed on either side of the dielectric. Some materials do better as dielectrics in terms of how much they resist electric fields (dielectric constant) and how much electric field they can take (dielectric strength). Capacitors store energy as charge between their plates, and the higher their capacitance is, the more energy they store with the same voltage. Capacitance is maximized when you have very low distance plates with very high surface area on a dielectric with high dielectric constant. Capacitors also smooth out changes in voltage.

An inductor is made with a coil of wire, usually hundreds of turns, wound around a central core. Like with capacitors, air can be used, but usually ferrites are used, which are alloys containing iron that made non-conductive. Inductors also can be made around a ring of ferrite, and a single ring can have two inductors (making a transformer, which can change voltage and current). Inductors smooth out changes in current, and sometimes disconnecting one can cause the magnetic field to collapse so fast that the air itself becomes a plasma. The ability to do this is measured by inductance, which is maximized when the permeability (which is a measure of how much the core amplifies/channels magnetic fields), turn count, and cross-sectional area are all maximized, while the length is minimized and the core is wound into a torus/doughnut shape, although inductance is also sensitive to ferromagnetic materials outside the coil.

A transformer, as mentioned before, is two inductors whose magnetic field is shared, so that one inductor can interact with another. If one inductor has lower inductance than the other, putting voltage in the small one will give you high voltage low current at the large one, putting current in the large one will give you low voltage high current at the small one, and vice versa for both. The amount a transformer multiplies current is inverse to the amount it multiplies voltage, conserving energy. Transformers can also have more than two coils. Ideal transformers have current and voltage perfectly linked on both sides, meaning they work with DC current (current that doesn't change), however in reality, they only work with AC current due to inductance not being infinite and leakage flux. This is actually somewhat useful, as it means that you can use the voltage spike from disconnecting one side to get an extremely large voltage on the other side (an ignition coil).

More advanced electronics, like semiconductor electronics and plasma technology, is harder to make, and is more complicated.

Dependencies

• Energy
• Energetics
• Fire
• Heat
• Electricity
• Generator

See also

• Biomass

References

This article uses material from the Wikipedia article Electricity, which is released under the Creative Commons Attribution-ShareAlike 3.0 Unported License (view authors).