. 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.
. 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
. 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
. 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. Ho
. 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 o
. 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 po
. 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, re
. 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 second
. 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 abilit
. Faradays and Amp
Generation and transmission
. 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 volta
. 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 c
Electricity in physics
. 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
. 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 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 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.
. 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 classifie
. 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 too
. 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. Whet
. 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 i
Voltage Current and Resistance
. 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 wat
Direct Current Versus Alternating Current
. 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
. 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 el
Everything Is Made Of Atoms
. 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 piece
. 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,
Types of electricity
. 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 elect
Wires conduct electricity
. 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
. 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.
. These parts of an atom have no charge. They are neutral and part of the nucleus of an atom with the protons.
. 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.