Mercury-vapor lamp and Related Topics

Fluorescent lamp

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Low-pressure mercury-vapor gas-discharge lamp that uses fluorescence to produce visible light.

Top: two non-integrated compact fluorescent lamps. Bottom: two fluorescent tube lamps. Both types require a ballast in the light fixture. A matchstick, left, is shown for scale.

Typical F71T12 100 W bi-pin lamp used in tanning beds. The (Hg) symbol indicates that this lamp contains mercury. In the US, this symbol is now required on all mercury-containing fluorescent lamps.

A "tombstone" style lamp-holder for T12 and T8 bi-pin fluorescent lamps

Inside the lamp end of a preheat bi-pin lamp. In this lamp, the filament is surrounded by an oblong metal cathode shield, which helps reduce lamp end darkening.

One of the first mercury vapor lamps invented by Peter Cooper Hewitt, 1903. It was similar to a fluorescent lamp without the fluorescent coating on the tube and produced greenish light. The round device under the lamp is the ballast.

Close-up of the cathodes of a germicidal lamp (an essentially similar design that uses no fluorescent phosphor, allowing the electrodes to be seen)

A germicidal lamp uses a low-pressure mercury-vapor glow discharge identical to that in a fluorescent lamp, but the uncoated fused quartz envelope allows ultraviolet radiation to transmit.

Different ballasts for fluorescent and discharge lamps

Thermal image of a helical fluorescent lamp.

A Sankey diagram of energy losses in a fluorescent lamp. In modern designs, the biggest loss is the quantum efficiency of converting high-energy UV photons to lower-energy visible light photons.

A cold-cathode fluorescent lamp from an emergency-exit sign. Operating at a much higher voltage than other fluorescents, the lamp produces a low-amperage glow discharge rather than an arc, similar to a neon light. Without direct connection to line voltage, current is limited by the transformer alone, negating the need for a ballast.

A preheat fluorescent lamp circuit using an automatic starting switch. A: Fluorescent tube, B: Power (+220 volts), C: Starter, D: Switch (bi-metallic thermostat), E: Capacitor, F: Filaments, G: Ballast

A preheat fluorescent lamp "starter" (automatic starting switch)

T12 fluorescent tubes. The first two are rapid start, (for "tombstone" and socket holders respectively) while the third is an instant-start lamp. The instant-start has a characteristic, rounded, single pin, for plugging into the spring-loaded socket holders.

A rapid-start "iron" (magnetic) ballast continually heats the cathodes at the ends of the lamps. This ballast runs two F40T12 lamps in series.

Electronic ballast for fluorescent lamp, 2×58 W

Electronic ballasts and different compact fluorescent lamps

This tube, which was turned on and off regularly, could no longer start after enough thermionic emission mix had sputtered from the cathodes. The vaporized material adheres to the glass surrounding the electrodes, causing it to darken and turn black.

Closeup of the filament on a low pressure mercury gas discharge lamp showing white thermionic emission mix coating on the central portion of the coil acting as hot cathode. the coating is sputtered away every time the lamp starts, resulting in lamp failure.

Compact fluorescent lamp that has reached end of life because of mercury adsorption. Light is produced only by the base argon fill.

Light from a fluorescent tube lamp reflected by a CD shows the individual bands of color.

The color temperature of different electric lamps

$A helical cool-white fluorescent lamp reflected in a diffraction grating reveals the various spectral lines which make up the light.$

Fluorescent spectra in comparison with other forms of lighting. Clockwise from upper left: Fluorescent lamp, incandescent bulb, candle flame and LED lighting.

Magnetic ballasts have a low power factor, when used without a capacitor, which increases current drawn by the lighting fixture.

The "beat effect" problem created when shooting photos under standard fluorescent lighting

Capacitive coupling with high-voltage power lines can light a lamp continuously at low intensity.

At about the same time that Moore was developing his lighting system, Peter Cooper Hewitt invented the mercury-vapor lamp, patented in 1901.

Metal-halide lamp

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Electrical lamp that produces light by an electric arc through a gaseous mixture of vaporized mercury and metal halides .

Spectrum of a 175 watt metal halide lamp

Metal halide floodlights at a baseball field

Metal halide lamps were invented by Charles Proteus Steinmetz in 1912 and are now used in almost every city in the world.

A Philips MHN-TD 150W/842 linear/tubular metal-halide lamp lit up at half power

Electronic ballast for 35 W metal halide light bulbs

Output spectrum of a typical metal-halide lamp showing peaks at 385nm, 422nm, 497nm, 540nm, 564nm, 583nm (highest), 630nm, and 674nm.

400 W metal-halide lamp shortly after powering up

A low-bay light fixture using a high-wattage metal-halide lamp, of the type used in factories and warehouses

A Philips MHN-TD 150W/842 (150 watts, 4200 K) linear/tubular metal-halide lamp

A light source using a broad-spectrum metal-halide lamp pointing upward towards the sky

A metal-halide light bank at a softball field

A ceramic metal-halide lamp 70 Watt - screw fixture (aquarium)

Pictograms on the packaging of a 35 W lamp. The multitude of instructions is due to the higher complexity of use in comparison to other lamp types.

Developed in the 1960s, they are similar to mercury vapor lamps, but contain additional metal halide compounds in the quartz arc tube, which improve the efficiency and color rendition of the light.

Ultraviolet

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Form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30 PHz) to 400 nm (750 THz), shorter than that of visible light, but longer than X-rays.

A 380 nanometer UV LED makes some common household items fluoresce.

Ultraviolet photons harm the DNA molecules of living organisms in different ways. In one common damage event, adjacent thymine bases bond with each other, instead of across the "ladder". This "thymine dimer" makes a bulge, and the distorted DNA molecule does not function properly.

Sunburn effect (as measured by the UV index) is the product of the sunlight spectrum (radiation intensity) and the erythemal action spectrum (skin sensitivity) across the range of UV wavelengths. Sunburn production per milliwatt of radiation intensity is increased by nearly a factor of 100 between the near UV‑B wavelengths of 315–295 nm

Demonstration of the effect of sunscreen. The man's face has sunscreen on his right side only. The left image is a regular photograph of his face; the right image is of reflected UV light. The side of the face with sunscreen is darker because the sunscreen absorbs the UV light.

Signs are often used to warn of the hazard of strong UV sources.

UV damaged polypropylene rope (left) and new rope (right)

IR spectrum showing carbonyl absorption due to UV degradation of polyethylene

A portrait taken using only UV light between the wavelengths of 335 and 365 nanometers.

Aurora at Jupiter's north pole as seen in ultraviolet light by the Hubble Space Telescope.

A bird appears on many Visa credit cards when they are held under a UV light source

After a training exercise involving fake body fluids, a healthcare worker's personal protective equipment is checked with ultraviolet light to find invisible drops of fluids. These fluids could contain deadly viruses or other contamination.

A collection of mineral samples brilliantly fluorescing at various wavelengths as seen while being irradiated by UV light.

Effects of UV on finished surfaces in 0, 20 and 43 hours.

A low-pressure mercury vapor discharge tube floods the inside of a hood with shortwave UV light when not in use, sterilizing microbiological contaminants from irradiated surfaces.

Entomologist using a UV light for collecting beetles in Chaco, Paraguay.

It is also produced by electric arcs and specialized lights, such as mercury-vapor lamps, tanning lamps, and black lights.

A modern American ballast for powering a variety of American T8 fluorescent office lamps.

Electrical ballast

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Device placed in series with a load to limit the amount of current in an electrical circuit.

Variety of ballasts for fluorescent and other discharge lamps

A typical 230V, 50hz series choke ballast (inductor) used in older lighting. This example is from a tanning bed. It requires a starter switch (below).

A lamp starter, required with some inductor type ballasts. It connects the two ends of the lamp to preheat them for one second before lighting.

A fluorescent lamp, a device with negative differential resistance. In operation, an increase in current through the fluorescent tube causes a drop in voltage across it. If the tube were connected directly to the power line, the falling tube voltage would cause more and more current to flow, until it destroyed itself. To prevent this, fluorescent tubes are connected to the power line through a ballast. The ballast adds positive impedance (AC resistance) to the circuit to counteract the negative resistance of the tube, limiting the current.

Several American magnetic ballasts for fluorescent lamps. The top is a high-power factor rapid start series ballast for two 30–40 W lamps. The middle is a low power factor preheat ballast for a single 30–40 W lamp while the bottom ballast is a simple inductor used with a 15 W preheat lamp.

An American magnetic ballast for signs in an aluminum sign frame. Sign ballasts are heavier duty than other ballasts because the cooler outdoor temperatures increase the energy
required to start a fluorescent tube. They are sized based on the total tube length used.

Typical European 230V series choke ballast 40W T12 or 36W T8 fluorescent lamps.

Electronic ballast of a compact fluorescent lamp

Self ballasted mercury-vapor lamps incorporate ordinary tungsten filaments within the overall envelope of the lamp to act as the ballast, and it supplements the otherwise lacking red area of the light spectrum produced.

Germicidal lamps are simple low-pressure mercury vapor discharges in a fused quartz envelope.

Gas-discharge lamp

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Electric discharge through an ionized gas, a plasma.

15 kW xenon short-arc lamp used in IMAX projectors

High pressure mercury-vapor lamps are the oldest high pressure lamp type and have been replaced in most applications by metal halide and the high pressure sodium lamps.

A pound coin (density ~7.6 g/cm3) floats on mercury due to the combination of the buoyant force and surface tension.

Mercury (element)

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Chemical element with the symbol Hg and atomic number 80.

Mercury-discharge spectral calibration lamp

The symbol for the planet Mercury (☿) has been used since ancient times to represent the element

Native mercury with cinnabar, Socrates mine, Sonoma County, California. Cinnabar sometimes alters to native mercury in the oxidized zone of mercury deposits.

The bulb of a mercury-in-glass thermometer

A single-pole, single-throw (SPST) mercury switch

Amount of atmospheric mercury deposited at Wyoming's Upper Fremont Glacier over the last 270 years

EPA workers clean up residential mercury spill in 2004

The deep violet glow of a mercury vapor discharge in a germicidal lamp, whose spectrum is rich in invisible ultraviolet radiation.

Skin tanner containing a low-pressure mercury vapor lamp and two infrared lamps, which act both as light source and electrical ballast

The miniaturized Deep Space Atomic Clock is a linear ion-trap-based mercury ion clock, designed for precise and real-time radio navigation in deep space.

Gaseous mercury is used in mercury-vapor lamps and some "neon sign" type advertising signs and fluorescent lamps.

Peter Cooper Hewitt

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Cooper Hewitt's mercury vapor lamp, the forerunner of the fluorescent lamp

Portrait of Mrs. Peter Cooper Hewitt (1911-13), by Giovanni Boldini.

Cooper Hewitt lights used in film production (1916).

Peter Cooper Hewitt (May 5, 1861 – August 25, 1921) was an American electrical engineer and inventor, who invented the first mercury-vapor lamp in 1901.

Light

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Electromagnetic radiation within the portion of the electromagnetic spectrum that is perceived by the human eye.

The electromagnetic spectrum, with the visible portion highlighted

Beam of sun light inside the cavity of Rocca ill'Abissu at Fondachelli-Fantina, Sicily

$Due to refraction, the straw dipped in water appears bent and the ruler scale compressed when viewed from a shallow angle.$

Hong Kong illuminated by colourful artificial lighting.

$Thomas Young's sketch of a double-slit experiment showing diffraction. Young's experiments supported the theory that light consists of waves.$

Emission can be spontaneous, as in light-emitting diodes, gas discharge lamps (such as neon lamps and neon signs, mercury-vapor lamps, etc.) and flames (light from the hot gas itself—so, for example, sodium in a gas flame emits characteristic yellow light).

Street light

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Raised source of light on the edge of a road or path.

Detail of a street light with Cupid, at the Austrian Parliament Building (Vienna)

William Murdoch's house in Redruth, UK, the first domestic house in the world to be lit by gas

Demonstration of Yablochkov's arc lamp on the Avenue de l'Opera in Paris (1878), the first form of electric street lighting

Heritage lamp post in the City Botanic Gardens, Brisbane

Map of Tamworth, New South Wales, showing the position of leads and lights along the network of city streets in 1888

The distinctive monochromatic yellow glow from a low-pressure sodium lamp in the UK

A low-pressure sodium lamp running at full brightness

Old-style street light with lamps near the Mönchbruch hunting lodge near Rüsselsheim am Main, Germany

Sign in Leeds, UK indicating part-night lighting, meant to save energy and reduce light pollution.

A street lamp with a telecell installed. This communicates with the council's central management system.

Decorative but functional lamps in the Plaza at sunset, Samaipata, Bolivia

High-mast lighting along Highway 401 in Ontario, Canada

Conventional streetlights are used instead of high-mast lighting near airport runway approaches due to the negative effects caused by the latter.

Safe cycling with a dedicated bicycle path with street lights in London

Lights similar to street lights are used at train stations; these are at London King's Cross

A man performing maintenance on a street light in Tokyo

A Fietspad or bicycle path in the Netherlands with street lighting

New York City fire alarm pull box indicator mounted on street light

Typical base and escutcheon of a farola fernandina

Street light in Ferdinand VII style near the Royal Palace of Aranjuez

Street light from the 1950s attached to a utility pole in New Jersey

These lamps are advantageous over other lamps such as mercury and metal halide lamps because low pressure sodium lamps emit lower intensity, monochromatic light.