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Mercury-vapor lamps produce light by passing an electric arc through solid mercury.
Answer: False
The fundamental principle of mercury-vapor lamp operation involves an electric arc passing through *vaporized* mercury, not solid mercury.
The outer glass bulb of a mercury-vapor lamp is primarily responsible for containing the electric arc.
Answer: False
The fused quartz arc tube, not the outer glass bulb, is the component primarily responsible for containing the high-temperature electric arc within a mercury-vapor lamp.
Mercury-vapor lamps operate at very low internal pressures, typically below 0.1 atmospheres.
Answer: False
Upon reaching operating temperature, mercury-vapor lamps maintain an internal pressure of approximately one atmosphere within the arc tube, not significantly below 0.1 atmospheres.
Argon gas is used in mercury-vapor lamps primarily to produce the main visible light output.
Answer: False
Argon gas is present in mercury-vapor lamps to facilitate the initiation of the electric arc upon startup. The primary visible light output is generated by the excited mercury vapor itself.
The resistor near the starter electrode in some mercury lamps helps to cool the arc tube.
Answer: False
The resistor associated with the starter electrode in some mercury lamps is designed to supply current to the starter, facilitating arc initiation, not to cool the arc tube.
Medium-pressure mercury-vapor lamps emit light primarily in the ultraviolet range (below 300 nm).
Answer: False
Medium-pressure mercury-vapor lamps emit light across a broader spectrum, extending from the ultraviolet range (approximately 200 nm) into the visible spectrum (up to 600 nm), not primarily in the UV range below 300 nm.
What is the primary mechanism by which a mercury-vapor lamp produces light?
Answer: Passing an electric arc through vaporized mercury.
Mercury-vapor lamps generate light through an electric arc that passes through vaporized mercury, causing the mercury atoms to become excited and emit photons.
Which component of a mercury-vapor lamp is primarily responsible for containing the electric arc itself?
Answer: The fused quartz arc tube.
The fused quartz arc tube is the component specifically designed to contain the high-temperature electric arc within a mercury-vapor lamp due to its resistance to heat and chemical inertness.
What role does argon gas play when a mercury-vapor lamp is initially turned on?
Answer: It helps initiate the electric arc.
Argon gas, present in low-pressure form within the lamp, ionizes upon power application, initiating the electric arc which then heats and vaporizes the mercury.
What is the primary function of the outer bulb in a mercury-vapor lamp?
Answer: To provide thermal insulation and UV shielding.
The primary functions of the outer glass bulb in a mercury-vapor lamp are to provide thermal insulation for the arc tube and to shield users from harmful ultraviolet radiation.
What is the approximate internal pressure inside the arc tube of a mercury-vapor lamp when it is operating at full temperature?
Answer: 1 atmosphere
When operating at full temperature, the internal pressure within the arc tube of a mercury-vapor lamp is approximately one atmosphere.
Peter Cooper Hewitt invented the mercury-vapor lamp in the early 20th century.
Answer: True
Peter Cooper Hewitt is credited with developing the first mercury-vapor lamp to achieve widespread success, with his initial patent granted in 1901.
The U.S. patent for Peter Cooper Hewitt's mercury-vapor lamp was granted in 1903.
Answer: False
Peter Cooper Hewitt was granted U.S. patent 682,692 for his mercury-vapor lamp on September 17, 1901, not in 1903. An improved version was developed in 1903.
General Electric and Osram were key companies involved in developing modern mercury-vapor lamps in the 1930s.
Answer: True
During the 1930s, companies such as Osram-GEC and General Electric were instrumental in developing enhanced, contemporary forms of mercury-vapor lamps, contributing to their broad adoption for general illumination.
Who invented the first mercury-vapor lamp to achieve widespread success?
Answer: Peter Cooper Hewitt
Peter Cooper Hewitt is credited with developing the initial mercury-vapor lamp that achieved widespread commercial success, with his patent granted in 1901.
Mercury-vapor lamps have a luminous efficacy ranging from 35 to 55 lumens per watt.
Answer: True
Mercury-vapor lamps typically exhibit a luminous efficacy within the range of 35 to 55 lumens per watt, indicating a moderate level of energy efficiency compared to other lighting technologies.
A key advantage of mercury-vapor lamps is their exceptionally short lifespan, typically around 5,000 hours.
Answer: False
Mercury-vapor lamps are characterized by their long operational lifespans, often reaching approximately 24,000 hours, which is significantly longer than the 5,000 hours stated.
Color-corrected mercury lamps use a phosphor coating to convert UV emissions into red wavelengths, improving color rendition.
Answer: True
Color-corrected mercury lamps employ a phosphor coating that absorbs ultraviolet emissions and re-emits them as red wavelengths, thereby enhancing the overall color rendition of the light.
Mercury-vapor lamps achieve full light output almost instantly upon being switched on.
Answer: False
Mercury-vapor lamps require a warm-up period, typically ranging from four to seven minutes, to achieve their full light output after being switched on.
When first switched on, a mercury-vapor lamp immediately emits bright, white light.
Answer: False
Upon initial activation, a mercury-vapor lamp emits a dim, dark blue glow. It requires a warm-up period of several minutes to reach its full, brighter light output.
A 125W mercury-vapor lamp typically operates at a higher current than a 400W lamp.
Answer: False
A 125W mercury-vapor lamp typically draws approximately 1.15 amperes, while a 400W lamp draws approximately 3.25 amperes. Therefore, the 400W lamp operates at a higher current.
The phosphor coating in color-corrected lamps adds primarily blue wavelengths to the light output.
Answer: False
The phosphor coating in color-corrected mercury lamps converts ultraviolet emissions into red wavelengths, improving color rendition by adding red light, not blue.
Color-corrected mercury-vapor lamps operating outdoors can sometimes be identified by a blue halo effect.
Answer: True
Color-corrected mercury-vapor lamps can frequently be identified outdoors by the presence of a distinct blue halo encircling the emitted light.
The strongest emission lines for mercury vapor occur only in the ultraviolet spectrum.
Answer: False
While mercury vapor emits strongly in the ultraviolet spectrum, its strongest emission lines also include visible wavelengths such as violet, blue, green, and yellow.
Compared to incandescent lamps, mercury-vapor lamps offer:
Answer: Higher luminous efficacy and longer lifespan.
Mercury-vapor lamps provide significantly higher luminous efficacy (lumens per watt) and a much longer operational lifespan compared to traditional incandescent lamps.
What is the typical luminous efficacy range for mercury-vapor lamps?
Answer: 35-55 lumens per watt
The luminous efficacy of mercury-vapor lamps typically falls within the range of 35 to 55 lumens per watt, indicating a moderate level of energy efficiency.
Why are clear mercury lamps often unsuitable for applications like retail lighting?
Answer: Their greenish light is unflattering to skin tones.
Clear mercury lamps emit a greenish hue that is often considered unflattering to human skin tones and can distort the appearance of colors, making them unsuitable for retail environments.
How do color-corrected mercury lamps improve light quality?
Answer: By adding red wavelengths using a phosphor coating.
Color-corrected mercury lamps utilize a phosphor coating that converts ultraviolet emissions into red wavelengths, thereby enhancing spectral balance and improving color rendition.
What is the typical warm-up time for a mercury-vapor lamp to reach full brightness?
Answer: 4 to 7 minutes
Mercury-vapor lamps require a warm-up period, generally ranging from four to seven minutes, prior to achieving their maximum light output.
What is a significant disadvantage of mercury-vapor lamps concerning their light spectrum?
Answer: Their spectrum is narrow, lacking red wavelengths, making colors appear unnatural.
A significant disadvantage of mercury-vapor lamps is their narrow spectral output, which lacks sufficient red wavelengths, causing colors to appear unnatural or distorted.
What is a characteristic spectral emission line of mercury vapor in the violet range?
Answer: 404.7 nm
The spectral emission line of mercury vapor in the violet range is approximately 404.7 nm (designated as the H-line).
What is the characteristic initial visual effect when a mercury-vapor lamp is switched on?
Answer: A dim, dark blue glow.
Upon initial activation, a mercury-vapor lamp typically exhibits a dim, dark blue glow, indicative of the early stages of arc formation and mercury vaporization before full brightness is achieved.
Mercury-vapor lamps are considered 'negative resistance' devices, meaning their resistance increases with current.
Answer: False
Mercury-vapor lamps exhibit 'negative resistance,' meaning their electrical resistance decreases as the current flowing through them increases. This characteristic necessitates a ballast.
An electrical ballast is optional for standard mercury-vapor lamps as they can self-regulate current.
Answer: False
An electrical ballast is essential for standard mercury-vapor lamps. Due to their negative resistance characteristic, they cannot self-regulate current and would self-destruct without a ballast to limit it.
Self-ballasted mercury-vapor lamps require an external ballast for current regulation.
Answer: False
Self-ballasted mercury-vapor lamps are designed with an integrated filament that functions as a ballast, thereby eliminating the need for an external ballast.
After a power interruption, a mercury-vapor lamp can restrike immediately once power is restored.
Answer: False
Mercury-vapor lamps require a cooling period after a power interruption before they can restrike. The elevated internal pressure prevents immediate reignition.
What is the essential external component required for the operation of standard mercury-vapor lamps?
Answer: An electrical ballast
An electrical ballast is essential for standard mercury-vapor lamps to regulate the current flow, preventing the lamp from drawing excessive amperage due to its negative resistance characteristic.
The need for a ballast in mercury-vapor lamps is due to their characteristic of:
Answer: Negative resistance (resistance decreases with current).
Mercury-vapor lamps exhibit negative resistance, meaning their resistance drops as current increases. A ballast is required to limit this current and prevent lamp destruction.
Self-ballasted mercury-vapor lamps simplify installation because they:
Answer: Do not need an external ballast.
Self-ballasted mercury-vapor lamps simplify installation as they incorporate an internal ballast, eliminating the requirement for an external ballast unit.
What occurs immediately after a mercury-vapor lamp loses power?
Answer: It requires a brief cooling period before it can restrike.
Following a power interruption, the mercury-vapor lamp requires substantial cooling to reduce its internal pressure before it can restrike.
Due to their color quality, mercury-vapor lamps are ideal for retail environments where accurate color rendering is crucial.
Answer: False
Clear mercury-vapor lamps emit a greenish light that is generally considered unflattering to skin tones and merchandise, making them unsuitable for retail environments requiring accurate color rendering.
Metal halide lamps are considered less efficient and offer poorer color balance than mercury-vapor lamps.
Answer: False
Metal halide lamps are generally considered more efficient and offer superior color balance compared to mercury-vapor lamps, leading to their increasing adoption as replacements.
The use of mercury-vapor lamp UV light for water purification was first documented in the mid-20th century.
Answer: False
The application of ultraviolet light from mercury-vapor lamps for water treatment was documented as early as 1910, predating the mid-20th century.
Halogen lamps are sometimes used as backup light sources in fixtures designed for mercury-vapor lamps.
Answer: True
To provide immediate illumination during the cooling and restriking phase of a mercury-vapor lamp, many fixtures incorporate a secondary backup lamp, frequently a halogen lamp of comparable brightness.
Historically, incandescent lamps were sometimes used alongside mercury-vapor lamps to improve color rendering.
Answer: True
Before the widespread adoption of phosphors for color correction, mercury-vapor lamps were often operated concurrently with incandescent lamps to supplement the red wavelengths and improve perceived color quality.
Low-pressure sodium lamps are the least effective option for minimizing light pollution due to their broad spectrum.
Answer: False
Low-pressure sodium lamps are considered the most effective option for minimizing light pollution because they emit light in very narrow spectral lines, facilitating easier filtering.
LED bulbs are not compatible with existing mercury-vapor fixtures.
Answer: False
Manufacturers are producing LED bulbs specifically designed to be compatible with existing mercury-vapor fixtures, often without requiring modifications to the fixture.
Mercury-vapor lamps are still commonly used for street lighting in Germany and France.
Answer: False
Mercury-vapor lamps are not commonly used for street lighting in Germany and France; their use is more prevalent in countries like the United States, Canada, and Japan.
High-powered mercury-vapor lamps are used in the printing industry for UV curing of inks.
Answer: True
High-powered mercury-vapor lamps are commonly utilized in the printing industry for UV curing, a process employed to rapidly solidify and harden inks.
Ultra-high-performance (UHP) lamps are a type of mercury-vapor lamp used in modern digital video projectors.
Answer: True
Specialized ultra-high-pressure mercury-vapor lamps, designated as Ultra-high-performance (UHP) lamps, are frequently utilized as the light source in digital video projectors.
A thermal shorting switch in metal halide lamps prevents halide buildup on the starting electrode.
Answer: True
The 'thermal shorting switch' in certain metal halide lamps serves to eliminate potential differences between electrodes after ignition, thereby preventing halide buildup on the starting electrode and protecting the glass-metal seal.
Which technology is increasingly replacing mercury-vapor lamps due to better efficiency and color?
Answer: Metal halide lamps
Metal halide lamps are progressively supplanting mercury-vapor lamps due to their superior luminous efficacy and enhanced color balance.
What historical application of mercury-vapor lamp UV light was documented as early as 1910?
Answer: Water treatment
The application of ultraviolet light from mercury-vapor lamps for the purpose of water treatment was documented as early as 1910.
What alternative bulb types are offered for use in existing mercury-vapor fixtures?
Answer: Compact fluorescent (CFL) and LED bulbs.
Manufacturers produce replacement bulbs, including compact fluorescent (CFL) and light-emitting diode (LED) bulbs, designed for compatibility with existing mercury-vapor fixtures.
Which type of lighting is considered the best choice for minimizing light pollution?
Answer: Low-pressure sodium lamps
Low-pressure sodium lamps are generally regarded as the optimal choice for minimizing light pollution due to their emission of light in highly narrow spectral lines, which facilitates more effective filtering.
What industrial process commonly utilizes high-powered mercury-vapor lamps?
Answer: UV curing of inks
High-powered mercury-vapor lamps are commonly utilized in the printing industry for UV curing, a process employed to rapidly solidify and harden inks.
How do mercury-vapor lamps without phosphor coatings compare to low-pressure sodium lamps regarding light pollution?
Answer: They are the second-best option after low-pressure sodium lamps.
Mercury-vapor lamps without phosphor coatings are regarded as the second most effective option for mitigating light pollution, following low-pressure sodium lamps, due to their relatively discrete spectral output.
What is the purpose of the 'thermal shorting switch' in some metal halide lamps (related technology)?
Answer: To eliminate potential differences between electrodes after ignition.
The 'thermal shorting switch' in certain metal halide lamps serves to eliminate potential differences between the main electrode and the starting electrode after the lamp has ignited, preventing damage to the glass-metal seal.
High-pressure mercury-vapor lamps are useful in molecular spectroscopy because they provide:
Answer: Broadband continuum energy at millimeter and terahertz wavelengths.
High-pressure mercury-vapor lamps function as valuable and cost-effective sources in molecular spectroscopy, providing broadband continuum energy across millimeter and terahertz wavelengths, derived from their plasma's high electron temperature.
The 185 nm emission line from mercury lamps, when using synthetic quartz, can produce ozone.
Answer: True
The 185 nm ultraviolet emission line, which can pass through synthetic quartz, has the potential to create ozone in an oxygen-rich atmosphere, posing a health hazard.
The European Union banned mercury-vapor lamps for lighting purposes in 2008.
Answer: False
The European Union implemented a ban on low-efficiency mercury-vapor lamps for lighting purposes in 2015, not 2008.
In the United States, ballasts for general illumination mercury-vapor lamps were banned starting January 1, 2008.
Answer: True
The ban on ballasts for general illumination mercury-vapor lamps in the United States became effective on January 1, 2008, excluding specialty applications.
The US Department of Energy decided in 2015 to implement stricter regulations for mercury vapor HID lamps due to significant energy savings.
Answer: False
In 2015, the U.S. Department of Energy decided not to implement proposed regulations for mercury vapor HID lamps because they were not projected to yield substantial energy savings.
The short-wave UV-C radiation produced by mercury lamp arc tubes poses no health risk.
Answer: False
The short-wave UV-C radiation emitted by the arc tube of mercury-vapor lamps poses a significant health risk, capable of causing burns to the skin and eyes.
Breaking the outer glass jacket of a mercury lamp prevents UV exposure.
Answer: False
Breaking the outer glass jacket of a mercury lamp does not prevent UV exposure; in fact, it can increase the risk of exposure to hazardous UV-C radiation from the inner arc tube.
The 365 nm UV radiation from mercury-vapor lamps can cause polycarbonate plastics to discolor and turn yellow.
Answer: True
Mercury-vapor lamps emit a considerable quantity of 365 nm ultraviolet radiation, which can degrade certain plastics, such as polycarbonate, leading to discoloration and a yellowed appearance over time.
What is a potential health hazard associated with the UV radiation emitted by mercury-vapor lamps?
Answer: Eye inflammation and skin burns.
The short-wave UV-C radiation emitted by the arc tube of mercury-vapor lamps poses a health risk, capable of causing inflammation to the eyes and burns to the skin.
The 365 nm UV radiation emitted by mercury-vapor lamps can cause which effect on certain plastics?
Answer: Discoloration and yellowing.
The 365 nm ultraviolet radiation emitted by mercury-vapor lamps can degrade certain plastics, such as polycarbonate, leading to discoloration and a yellowed appearance over time.
Which country implemented a ban on low-efficiency mercury-vapor lamps in 2015?
Answer: European Union
The European Union enacted a prohibition on the utilization of low-efficiency mercury-vapor lamps for lighting purposes in the year 2015.
What was the effective date for the ban on ballasts used in general illumination mercury-vapor lamps in the US?
Answer: January 1, 2008
The ban on ballasts for general illumination mercury-vapor lamps in the United States became effective on January 1, 2008.
Why did the US Department of Energy decide *not* to implement proposed regulations for mercury vapor HID lamps in 2015?
Answer: The proposed regulations were not projected to yield substantial energy savings.
The U.S. Department of Energy did not implement the proposed regulations for mercury vapor HID lamps because they were not projected to yield substantial energy savings.
What is a potential hazard associated with the 185 nm UV emission line from mercury-vapor lamps made with synthetic quartz?
Answer: It can create ozone in the surrounding atmosphere.
The 185 nm ultraviolet emission line, which can pass through synthetic quartz, has the potential to create ozone in an oxygen-rich atmosphere, posing a health hazard.