spark gap

Whilst mains voltages are capable of delivering fatal shocks and may constitute high-voltage hazards, they cannot jump significant distances, so they are dangerous only if touched. Therefore standards bodies do not generally refer to them as high voltages. Various safety and insurance organizations consider anything outside of the ELV range (i.e. greater than 50 V) to be dangerous and in need of regulation. Voltages above this range are capable of producing heart fibrillation if they produce electric currents in body tissues wh ...

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High voltage, High voltage - Safety and insurance industry, High voltage - Sparks in air, High voltage - Science classroom devices, High voltage - Electrostatic attraction/repulsion, High voltage - Power lines, High voltage - Arc flash hazard, High voltage - Explosion Hazard, High voltage - Toxic gases, High voltage - Lightning, High voltage - External USA Catalog Standards and codes / Guideline links, High voltage - External articles

Read more here: » High voltage: Encyclopedia II - High voltage - Safety and insurance industry

The word spark has several meanings: In electricity, "spark" usually refers to a momentary electrostatic discharge across a spark gap. It can also refer to a continuous electric arc or a corona discharge. A spark may be a small airborne ember or particle of glowing, hot metal from a fire, grinding machine, the heat from an electric spark as above, or the like. SPARK programming language Small Portable Adjustable Real-time Kernel, by Real Time Microsystems ...

Including:

• Spark - Common misspellings

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Piezoelectricity is the ability of certain crystals to generate a voltage in response to applied mechanical stress. The word is derived from the Greek piezein, which means to squeeze or press. The piezoelectric effect is reversible in that piezoelectric crystals when subjected to an externally applied voltage, can change shape by a small amount. The deformation, about 0.1% of the original dimension in PZT, is of the order of nanometers, but nevertheless finds useful applications such as the production and detection of sound, ge ...

Including:

• Piezoelectricity - Mechanism
• Piezoelectricity - Crystal classes
• Piezoelectricity - Mathematical description
• Piezoelectricity - History
• Piezoelectricity - Materials
• Piezoelectricity - Applications
• Piezoelectricity - High-voltage sources
• Piezoelectricity - Sensors
• Piezoelectricity - Actuators
• Piezoelectricity - Frequency standards
• Piezoelectricity - Piezoelectric motors
• Piezoelectricity - Ultrasonic transducers

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Transmission lines for electric power always use voltages in excess of 50 volts, so contact with or close approach to the line conductors presents a danger of electrocution. Contact with overhead wires is a frequent cause of injury or death. Metal ladders, farm equipment, boat masts, construction machinery, television antennas, and similar objects are frequently involved in fatal contact with overhead wires. Digging into a buried cable can also be dangerous to workers at the excavation site. Digging equipment (either hand tools or machine dr ...

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High voltage, High voltage - Safety and insurance industry, High voltage - Sparks in air, High voltage - Science classroom devices, High voltage - Electrostatic attraction/repulsion, High voltage - Power lines, High voltage - Arc flash hazard, High voltage - Explosion Hazard, High voltage - Toxic gases, High voltage - Lightning, High voltage - External USA Catalog Standards and codes / Guideline links, High voltage - External articles

Read more here: » High voltage: Encyclopedia II - High voltage - Power lines

The crystal radio receiver (also known as a crystal set) was first built circa 1900 by Greenleaf Whittier Pickard, who used crystalline minerals to detect radio signals. Crystal radio receiver - History. Crystal radio receiver - Early years. People first built and used simple and inexpensive crystal radio sets without batteries or electrical power. Even though vacuum tube radios were common following World War I, crystal radios remained popular, especially among be ...

Including:

• Crystal radio receiver - History
• Crystal radio receiver - Early years
• Crystal radio receiver - 1920s and 1930s
• Crystal radio receiver - 1940s
• Crystal radio receiver - Later years
• Crystal radio receiver - Composition
• Crystal radio receiver - Espionage

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Telegraphy (from the Greek words tele = far and graphein = write) is the long-distance transmission of written messages without physical transport of letters, originally over wire. Radiotelegraphy or wireless telegraphy transmits messages using radio. As Albert Einstein put it, "Wire telegraph is a kind of a very, very long cat. You pull his tail in New York and his head is meowing in Los Angeles. And radio operates exactly the same way. The only difference is that there is no cat." Telegraphy includes rece ...

Including:

• Telegraphy - Optical telegraphs and smoke signals
• Telegraphy - Electrical telegraphs
• Telegraphy - Radiotelegraphy
• Telegraphy - Telegraphic improvements
• Telegraphy - Telex
• Telegraphy - TWX
• Telegraphy - Arrival of the Internet
• Telegraphy - E-mail starts to displace telegraphy
• Telegraphy - Telegraphy as a legacy system

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The largest-scale sparks are those produced naturally by lightning. Each stroke carries hundreds of thousands of amperes, at potentials of upwards of a million volts, with hundreds of joules of energy released in each strike. Each stroke lasts for only tens of microseconds. Hazards due to lightning obviously include a direct strike on persons or property. However, lightning can also create dangerous voltage gradients in the earth, and can charge extended metal objects such as telephone cables, fences, and pipelines to dangerous voltages that ...

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High voltage, High voltage - Safety and insurance industry, High voltage - Sparks in air, High voltage - Science classroom devices, High voltage - Electrostatic attraction/repulsion, High voltage - Power lines, High voltage - Arc flash hazard, High voltage - Explosion Hazard, High voltage - Toxic gases, High voltage - Lightning, High voltage - External USA Catalog Standards and codes / Guideline links, High voltage - External articles

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The dielectric breakdown strength of dry air at typical room temperature and sea-level pressure is about 33 kV per cm. [1] High voltages, i.e. strong electric fields produce violet-colored corona discharge in air, as well as visible sparks. Voltages below about 500-700 volts cannot produce easily visible sparks or glows in air at atmospheric pressure, so by this rule these voltages are 'low.' However, under conditions of low atmospheric pressure (such as in high-altitude aircraft), or in an environment of noble gas such as argon, neon, etc., ...

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High voltage, High voltage - Safety and insurance industry, High voltage - Sparks in air, High voltage - Science classroom devices, High voltage - Electrostatic attraction/repulsion, High voltage - Power lines, High voltage - Arc flash hazard, High voltage - Explosion Hazard, High voltage - Toxic gases, High voltage - Lightning, High voltage - External USA Catalog Standards and codes / Guideline links, High voltage - External articles

Read more here: » High voltage: Encyclopedia II - High voltage - Sparks in air

Image:Danger High voltage Keep out.JPG Transmission lines for electric power always use voltages in excess of 50 volts, so contact with or close approach to the line conductors presents a danger of electrocution. Contact with overhead wires is a frequent cause of injury or death. Metal ladders, farm equipment, boat masts, construction machinery, television antennas, and similar objects are frequently involved in fatal contact with overhead wires. Digging into a buried cable can also be dangerous to workers at the excavation site. Digging equ ...

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High voltage, High voltage - Safety and insurance industry, High voltage - Sparks in air, High voltage - Science classroom devices, High voltage - Electrostatic attraction/repulsion, High voltage - Power lines, High voltage - Arc flash hazard, High voltage - Explosion Hazard, High voltage - Toxic gases, High voltage - Lightning, High voltage - External USA Catalog Standards and codes / Guideline links, High voltage - External articles

Read more here: » High voltage: Encyclopedia II - High voltage - Power lines

A high voltage is not necessarily dangerous. Physics demonstration devices such as Van de Graaff generators and Wimshurst machines can produce voltages approaching one million volts, yet at worst they deliver a brief sting. These devices have a limited amount of stored energy, so the current produced is low and usually for a short time. During the discharge, these machines apply high voltage to the body for only a millionth of a second or less. The discharge may involve extremely high power over very short periods, but in order to produce he ...

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High voltage, High voltage - Safety and insurance industry, High voltage - Sparks in air, High voltage - Science classroom devices, High voltage - Electrostatic attraction/repulsion, High voltage - Power lines, High voltage - Arc flash hazard, High voltage - Explosion Hazard, High voltage - Toxic gases, High voltage - Lightning, High voltage - External USA Catalog Standards and codes / Guideline links, High voltage - External articles

Read more here: » High voltage: Encyclopedia II - High voltage - Science classroom devices

Even voltages insufficient to break down air can be associated with enough energy to ignite atmospheres containing flammable gases or vapours, or suspended dust. For example, air containing hydrogen gas or natural gas or gasoline vapor can be ignited by sparks produced by electrical apparatus. Examples of industrial facilities with hazardous areas are petrochemical refineries, chemical plants, grain elevators, and some kinds of coal mines. Measures taken to prevent such explosions include: Intrinsic safety, which is appar ...

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High voltage, High voltage - Safety and insurance industry, High voltage - Sparks in air, High voltage - Science classroom devices, High voltage - Electrostatic attraction/repulsion, High voltage - Power lines, High voltage - Arc flash hazard, High voltage - Explosion Hazard, High voltage - Toxic gases, High voltage - Lightning, High voltage - External USA Catalog Standards and codes / Guideline links, High voltage - External articles

Read more here: » High voltage: Encyclopedia II - High voltage - Explosion Hazard

The identity of the original inventor of radio, at the time called wireless telegraphy, is contentious. The key invention for the beginning of "wireless transmission of data using the entire frequency spectrum" [spark-gap radio] has been attributed to both Nikola Tesla, Guglielmo Marconi, and Alexander Popov. History of radio - Radio's prehistory 19th century. In 1820, Hans Christian Ørsted discovered the relationship between electricity and magnetism in a very simple experiment. He demonstrated that a wi ...

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History of radio, History of radio - Origins and developments, History of radio - Radio's prehistory 19th century, History of radio - Wireless beginnings, History of radio - Radio communication, History of radio - Radio factory, History of radio - Spark-gap wireless telegraphy 1896–1920, History of radio - Audio broadcasting 1915–Present, History of radio - Radio broadcasting beginnings, History of radio - FM radio, History of radio - 20th century developments, History of radio - Telex on Radio, History of radio - 21st century development, History of radio - Exotic technologies, History of radio - Television

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The invention of the device is credited to David Edward Hughes, among others. Oliver Joseph Lodge, in his Royal Institute lectures ("The Work of Hertz and Some of His Successors") coined the term "coherer" and gained the "syntonic" (or tuning) patent from the United States Patent Office. In 1892, Edouard Branly invented a coherer (which was named after him). Also, Alexander Popov developed a device similar to the "Branly coherer" to ...

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Coherer, Coherer - History, Coherer - Description

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Crystal radio receiver - Early years. People first built and used simple and inexpensive crystal radio sets without batteries or electrical power. Even though vacuum tube radios were common following World War I, crystal radios remained popular, especially among beginning amateur radio enthusiasts, Boy Scouts and school children, who built crystal radios to learn basic electronics and communication. Early wireless telegraphy used spark gap plasma arc transmitters powered by alternating current generators a ...

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Crystal radio receiver, Crystal radio receiver - History, Crystal radio receiver - Early years, Crystal radio receiver - 1920s and 1930s, Crystal radio receiver - 1940s, Crystal radio receiver - Later years, Crystal radio receiver - Composition, Crystal radio receiver - Espionage

Read more here: » Crystal radio receiver: Encyclopedia II - Crystal radio receiver - History

A spark plug is composed of a shell, insulator and the conductor. It pierces the wall of the combustion chamber and therefore must also seal the combustion chamber against high pressures and temperatures, without deteriorating over long periods of time and extended use. Spark plug - Parts of the plug. The top of the spark plug contains a terminal to connect to the ignition system. The exact terminal construction varies depending on the use of the spark plug. Most passenger car spark plug wires snap ...

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Spark plug, Spark plug - Operation, Spark plug - Spark plug construction, Spark plug - Parts of the plug, Spark plug - Spark plug gap, Spark plug - Variations on the basic design, Spark plug - Sealing to the cylinder head, Spark plug - Tip protrusion, Spark plug - Heat range, Spark plug - Reading spark plugs, Spark plug - Indexing spark plugs

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Photoelectric effect - Early observations. In 1839, Alexandre Edmond Becquerel observed the photoelectric effect via an electrode in a conductive solution exposed to light. In 1873, Willoughby Smith found that selenium is photoconductive. Photoelectric effect - Hertz's spark gaps. Heinrich Hertz, in 1887, made observations of the photoelectric effect and of the production and reception of electromagnetic (EM) waves, published in the journal Annalen der Physik. His receiver cons ...

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Photoelectric effect, Photoelectric effect - Introduction, Photoelectric effect - History, Photoelectric effect - Early observations, Photoelectric effect - Hertz's spark gaps, Photoelectric effect - JJ Thomson: electrons, Photoelectric effect - Tesla's radiant energy, Photoelectric effect - Von Lenard's observations, Photoelectric effect - Einstein: light quanta, Photoelectric effect - Effect on wave-particle question, Photoelectric effect - Explanation, Photoelectric effect - Equations, Photoelectric effect - Uses and effects, Photoelectric effect - Electroscopes, Photoelectric effect - Photoelectron spectroscopy, Photoelectric effect - Spacecraft, Photoelectric effect - Moon dust

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Very early radio transmitters used a spark gap to produce radio-frequency oscillations in the transmitting antenna; these signals had a characteristic rapidly damped amplitude during each pulse of radiated energy. When alternators and later electronic oscillators became available, the signal strength remained constant during each code element, leading to the description of this technique as "continuous" waves. An unmodulated carrier has no bandwidth and conveys no information; the act of keying the carrier on and off produces a finite ...

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Continuous wave, Continuous wave - Radio, Continuous wave - Key clicks, Continuous wave - Laser physics

Read more here: » Continuous wave: Encyclopedia II - Continuous wave - Radio

Tesla coil - Transmission. A large Tesla coil of more modern design can operate at very high peak power levels, up to many megawatts (a million watts; hundreds of thousands of horsepower). It should therefore be adjusted and operated carefully, not only for efficiency and economy, but also for safety. If, due to improper tuning, the maximum voltage point occurs below the terminal, along the secondary coil, a discharge (spark), or possibly a ball of plasma, may break out and damage or destroy the coil wir ...

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Tesla coil, Tesla coil - History, Tesla coil - Early coils, Tesla coil - Disruptive Tesla coils, Tesla coil - Later coils, Tesla coil - Description, Tesla coil - Utilization and production, Tesla coil - Transmission, Tesla coil - Safety and precautions, Tesla coil - Air discharges, Tesla coil - Reception, Tesla coil - The skin effect myth, Tesla coil - Instances and devices, Tesla coil - Popularity, Tesla coil - Related Tesla patents, Tesla coil - Further reading and other references

Read more here: » Tesla coil: Encyclopedia II - Tesla coil - Utilization and production

A lightning rod is connected via a low-resistance wire or cable to the earth or water below, where the charge may be safely dissipated. Lightning rods sometimes possess a short circuit to the ground that is interrupted by a thin non-conductor over which lightning jumps. Ideally, the underground part of the assembly should reside in a muddy area, or an area that tends to become so during storms. If the underground cable will resist corrosion well, it may be covered in sal ...

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Lightning rod, Lightning rod - Arrestors, Lightning rod - Construction and uses, Lightning rod - History, Lightning rod - Europe, Lightning rod - United States, Lightning rod - Lightning Prevention, Lightning rod - Patents, Lightning rod - External articles and other resources

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By 1935 message routing was the last great barrier to full automation. Large telegraphy providers began to develop systems that used telephone-like rotary dialing to connect teletypes. These machines were called "telex". Telex machines first performed rotary-telephone-style pulse dialing, and then sent baudot code. This "type A" telex routing functionally automated message routing. The first wide-coverage telex network was implemented in Germany during the 1930s. The network was used t ...

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Telegraphy, Telegraphy - Optical telegraphs and smoke signals, Telegraphy - Electrical telegraphs, Telegraphy - Radiotelegraphy, Telegraphy - Telegraphic improvements, Telegraphy - Telex, Telegraphy - TWX, Telegraphy - Arrival of the Internet, Telegraphy - E-mail starts to displace telegraphy, Telegraphy - Telegraphy as a legacy system

Read more here: » Telegraphy: Encyclopedia II - Telegraphy - Telex