Molly Ayala
The word electric is derived from the Greek word for amber, elektron. The phenomenon of electricity is associated with stationary or moving electric charges, with the involved particle being the electron, which carries a negative charge. The presence of a positive or negative electric charge produces an electric field, and the motion of these charges creates an electric current, which in turn produces a magnetic field. Electrical energy is energy in the form of electricity, and electrical devices are those that work by means of electricity.
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What You'll Learn
Electric power and energy
Electric power is a measure of the rate of electrical energy transfer by an electric circuit per unit of time. The SI unit of electric power is the watt, and it is denoted by the letter P. The formula for power is given by P = I V, where V is the potential difference, I is the electric current, and P is the electric power. The power formula can also be rewritten as P = I^2R or P = V^2/R, where R is the resistance.
Electric energy is generated through the conversion of other forms of energy, such as mechanical, thermal, or chemical energy. It has a wide range of uses, including lighting, computer operation, motive power, and entertainment applications. Electric energy can be converted into other forms of energy, such as heat energy, light energy, and motion. For example, a fan converts electrical energy into mechanical energy, while a lightbulb converts electrical energy into light energy.
The electric energy of a set of charges at rest can be viewed from the standpoint of the work required to assemble the charges. Alternatively, the energy can be considered to reside in the electric field produced by the assembly of charges. Energy can also be stored in a capacitor as electrostatic energy.
Primary sources for driving generators include hydro and thermal power. Hydroelectric power is derived from generators and turbines driven by falling water. Most other electric energy is obtained from generators coupled with turbines driven by steam produced by nuclear reactors or the burning of fossil fuels such as coal, oil, and natural gas. Alternative electric energy sources with smaller shares of the market include solar cells, wind turbines, fuel cells, and geothermal power stations.
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Electric charge
The word "electric" is derived from the Greek word for amber, "elektron". The phenomenon of electricity was first discovered when ancient Greek philosophers observed that rubbing amber with a piece of cloth caused the amber to pick up light objects, such as feathers. This phenomenon is now known as static electricity.
When two objects are rubbed together, they can acquire equal and opposite charges, and an attractive force develops between them. This is known as Coulomb's law. The object that loses electrons becomes positively charged, and the other becomes negatively charged.
The presence of either a positive or negative electric charge produces an electric field. The motion of electric charges creates an electric current and generates a magnetic field. Electric potential, or voltage, is the energy required to move a unit charge between two points within an electric field. It is typically measured in volts.
Electric power is the rate of doing work, measured in watts. Electric utilities measure power using electricity meters, which keep a running total of the electric energy delivered to a customer. Electricity is a versatile form of energy that can be converted into motion or other forms of energy with high efficiency. It plays a central role in many modern technologies.
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Electric current
The conventional direction of current, also known as conventional current, is arbitrarily defined as the direction in which positive charges flow. In a conductive material, the moving charged particles that constitute the electric current are called charge carriers. In metals, which make up the wires and other conductors in most electrical circuits, the positively charged atomic nuclei of the atoms are held in a fixed position, and the negatively charged electrons are the charge carriers, free to move about in the metal. In other materials, notably semiconductors, the charge carriers can be positive or negative, depending on the dopant used. Positive and negative charge carriers may even be present at the same time, as happens in an electrolyte in an electrochemical cell.
A flow of positive charges gives the same electric current and has the same effect in a circuit as an equal flow of negative charges in the opposite direction. In alternating current (AC) systems, the movement of electric charge periodically reverses direction. AC is the form of electric power most commonly delivered to businesses and residences. In contrast, direct current (DC) refers to a system in which the movement of electric charge is in only one direction. Direct current is produced by sources such as batteries, thermocouples, solar cells, and commutator-type electric machines of the dynamo type.
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Electrostatic energy
Electrostatics is a branch of physics that deals with the study of electromagnetic phenomena that occur when there are no moving charges—i.e., after a static equilibrium has been established. Electrostatic phenomena arise from the forces that electric charges exert on each other. The mathematical methods of electrostatics make it possible to calculate the distributions of the electric field and of the electric potential from a known configuration of charges, conductors, and insulators.
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Electric potential difference
The term "electric" is derived from the Greek word for amber, "elektron". While some electrical phenomena have been known since ancient times, it is only in modern times that electricity has been put to practical use. Electricity is a phenomenon associated with stationary or moving electric charges. Electric charge is a fundamental property of matter, and electrons are the particles involved in electricity, carrying a negative charge.
The relationship between voltage and energy can be observed in batteries. As a battery discharges, some of its energy is used internally, and its terminal voltage drops. For example, headlights may dim due to a depleted car battery. The energy supplied by the battery can be calculated, but not all of it is available for external use. The change in potential energy for the battery is negative since it loses energy.
The concept of electric potential difference is also important in understanding the behaviour of electrons and ions. When electrons or ions are accelerated through a potential difference, they gain energy. This energy is numerically equal to the voltage through which they are accelerated. For example, a 5000-V potential difference produces 5000-eV electrons. This unit of energy is called an electron-volt (eV).
In summary, electric potential difference, or voltage, is a critical concept in electricity, representing the energy per unit of charge in a system. It is distinct from electrical potential energy and is closely related to the behaviour of charged particles, such as electrons and ions, as they move through electric fields.
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Frequently asked questions
Electricity is a set of physical phenomena associated with the presence and motion of matter that possesses an electric charge.
An electric charge is a fundamental property of matter and is carried by elementary particles. In electricity, the particle involved is the electron, which carries a negative charge.
Examples of electric currents include metallic conduction, where electrons flow through a conductor such as metal, and electrolysis, where ions (charged atoms) flow through liquids or plasmas.
