Electricity (3)

During the late 19th century, electrical engineering made great strides. People like Alexander Graham Bell, Thomas Edison, and Nikola Tesla helped turn electricity from a scientific curiosity into a practical tool for everyday life. In 1887, Heinrich Hertz discovered that electrodes illuminated with UV light were more likely to produce electric sparks. In 1905, Albert Einstein published a paper explaining the photoelectric effect, in which light is carried in quantized packets that energize electrons. This discovery led to the development of the quantum revolution and earned Einstein a Nobel Prize in Physics.

The first solid-state device was the "cat's-whisker detector," which was used in radio receivers in the 1900s. It used a wire that was placed lightly on a solid crystal, such as germanium, to detect radio signals through the contact junction effect. In solid-state electronics, current is confined to solid elements and compounds that are designed to switch and amplify it. This current can flow in two forms: as negatively charged electrons or as positively charged "holes." These charges and holes can be understood in terms of quantum physics, and the building material is often a crystalline semiconductor.

The transistor, a device that greatly advanced solid-state electronics, was invented in 1947 by John Bardeen and Walter Houser Brattain at Bell Labs. It was followed by the bipolar junction transistor in 1948. Electric charge arises from certain subatomic particles, such as electrons and protons. It gives rise to and interacts with the electromagnetic force, one of the four fundamental forces of nature. Charge is conserved, meaning that the net charge within an electrically isolated system will always remain constant. Charge can be transferred between bodies through direct contact or through a conductor, like a wire.

The movement of electric charge is known as an electric current, which is usually measured in amperes. Current can be carried by any moving charged particles, but it is most commonly carried by electrons. Electric current can flow through conductors but not through insulators. There are two main types of electric current: direct current (DC) and alternating current (AC). DC flows in only one direction, while AC periodically changes direction. The process of electrical conduction, in which electric current passes through a material, varies depending on the charged particles and the material they are traveling through. Examples of electric currents include metallic conduction, in which electrons flow through a conductor like metal, and electrolysis, in which ions flow through liquids or plasmas.

Electricity and magnetism have always been closely intertwined, with one giving rise to the other. In the early 1800s, Danish scientist Hans Christian Ørsted made a groundbreaking discovery when he found that a magnetic field was present around a wire carrying an electric current. This indicated that there was a relationship between electricity and magnetism, and that the interaction between the two was different from the gravitational and electrostatic forces that were then known. Further investigation by French scientist André-Marie Ampère revealed that parallel current-carrying wires exert a force on each other: wires with currents in the same direction are attracted, while those with currents in opposite directions are pushed apart. This interaction is mediated by the magnetic field produced by each current and is the basis for the definition of the ampere.

Electricity has fascinated people for centuries, and its study has led to many important discoveries and inventions. The concept of charge, which gives rise to the electrostatic force, was known in antiquity, but it wasn't until the 18th century that Charles-Augustin de Coulomb discovered that charge manifests itself in two opposing forms. This discovery led to the axiom that like-charged objects repel and opposite-charged objects attract. The force of electromagnetism, which is second only to the strong interaction in strength, operates over all distances and can be described by Coulomb's law. The movement of electric charge, or electric current, can be observed in various forms, such as metallic conduction and electrolysis. The process of electrical conduction and the effects of current, such as heating and electromagnetic interference, have been studied and utilized in engineering and household applications. The electric field, created by a charged body, results in a force on any other charges placed within it and can be visualized with lines of force. The concept of electric potential, which is closely linked to the electric field, is a scalar quantity that represents the energy required to bring a unit charge to a specific point. The relationship between magnetism and electricity, discovered by Ørsted and further investigated by Ampère, led to Faraday's invention of the electric motor and generator.

Electricity has the ability to drive chemical reactions, and this is utilized in a variety of ways. The most well-known example is probably the electroplating of metal, where an electric current is used to coat one metal with a layer of another. Electrolysis, the breaking down of a chemical compound using electricity, is also a commonly used process. For example, water can be split into hydrogen and oxygen using an electric current. In addition, portable devices such as laptops and cellphones are powered by rechargeable batteries, which utilize chemical reactions to store and release electrical energy. Overall, the relationship between electricity and chemistry has a wide range of practical applications in industry and everyday life.

Electric circuits are used in a vast array of machines and devices, from simple light switches to complex computers and factories. They allow for the control and management of electrical energy, making it possible to use electricity to perform tasks and meet our needs.

The basic components of an electric circuit are interdependent and work together to allow for the flow of electric charge. The resistor, for example, resists the flow of charge, while the capacitor stores it and the switch controls it. These components can be combined and connected in various ways to create circuits with specific functions and capabilities.

Electronic circuits, which contain active components like semiconductors, are used in a wide range of applications including computers, smartphones, and other electronic devices. These circuits often exhibit non-linear behavior, making their analysis and design more complex.

Overall, electric circuits are a fundamental part of our world, enabling the use of electricity to power and control an array of machines and devices.

An electric circuit is a path through which electric current can flow. It can be made up of a variety of components, including resistors, capacitors, switches, transformers, and electronic devices. Passive and linear components, such as resistors, simply oppose the flow of current and convert some of the energy into heat. Capacitors are devices that can store electric charge and energy in an electric field, while inductors are conductors that store energy in a magnetic field in response to current. The units of resistance, capacitance, and inductance are the ohm, farad, and henry, respectively. These concepts are fundamental to the operation of many electronic devices and systems.