physical phenomena associated with the presence and flow of electric charge / From Wikipedia, the free encyclopedia
Electricity is the presence and flow of electric current. Using electricity, we can transfer energy in ways that allow us to do simple chores. Its best-known form is the flow of electrons through conductors such as copper wires.
|Electricity · Magnetism · Magnetic permeability|
Electric charge • Coulomb's law •
Electric field • Electric flux •
Gauss's law • Electric potential energy •
Electric potential • Electrostatic induction •
Electric dipole moment • Polarization density
Ampère's law • Electric current • Magnetic field •
Magnetization • Magnetic flux • Biot–Savart law •
Magnetic dipole moment • Gauss's law for magnetism
Lorentz force law • emf • Electromagnetic induction • Faraday’s law • Lenz's law • Displacement current • Maxwell's equations • EM field • Electromagnetic radiation • Liénard–Wiechert potential • Maxwell tensor • Eddy current
Electrical conduction • Electrical resistance • Capacitance •
Inductance • Impedance • Resonant cavities • Waveguides
Electromagnetic tensor • EM Stress-energy tensor • Four-current • Electromagnetic four-potential
The word "electricity" is sometimes used to mean "electrical energy". They are not the same thing: electricity is a transmission medium for electrical energy, like sea water is a transmission medium for wave energy. An item which allows electricity to move through it is called a conductor. Copper wires and other metal items are good conductors, allowing electricity to move through them and transmit electrical energy. Plastics are a poor conductor (they are insulators) and don't allow much electricity to move through them. They stop the transmission of electrical energy.
Electrical energy can be made naturally (such as lightning), or by people (such as in a generator). It can be used to power machines and electrical devices. When electrical charges are not moving, electricity is called static electricity. When the charges are moving they are an electric current, sometimes called 'dynamic electricity'. Lightning is the most known - and dangerous - kind of electric current in nature, but sometimes static electricity causes things to stick together in nature as well.
Electricity can be dangerous, especially around water because water is a form of good conductor as it has impurities like salt in it. Salt can help electricity flow. Since the nineteenth century, electricity has been used in every part of our lives. Until then, it was just a curiosity seen in the lightning of a thunderstorm.
Electrical energy can be created if a magnet passes close to a metal wire. This is the method used by a generator. The biggest generators are in power stations. Electrical energy can also be released by combining chemicals in a jar with two different kinds of metal rods. This is the method used in a battery. Static electricity can be created through the friction between two materials - for instance a wool cap and a plastic ruler. This may make a spark. Electrical energy can also be created using energy from the sun, as in photovoltaic cells.
Electrical energy arrives at homes through wires from the places where it is made. It is used by electric lamps, electric heaters, etc. Many appliances such as washing machines and electric cookers use electricity. In factories, electrical energy powers machines. People who work with electricity and electrical devices in homes and factories are called "electricians".