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Why are low pressure mercury-vapour lamps coated with phosphors?
Low-pressure mercury-vapour lamps are coated with phosphors to convert the ultraviolet light emitted by the mercury into visible light that is more useful for general lighting purposes. This process allows the lamp to produce a broader spectrum of light, making it more appealing and efficient for human vision.
Who invented the real fluorescent lamp?
The real fluorescent lamp was invented by the German-American engineer and inventor, Peter Cooper Hewitt, in 1901. His lamp used an electric arc in mercury vapor to produce a blue-green light, which was an early precursor to modern fluorescent lighting.
Principle of operation of UV lamp?
A fluorescent lamp or fluorescent tube is a gas-discharge lamp that uses electricity to excite mercury vapor. The excited mercury atoms produce short-wave ultraviolet light that then causes a phosphor to fluoresce, producing visible light. A fluorescent lamp converts electrical power into useful light more efficiently than an incandescent lamp. Lower energy cost typically offsets the higher initial cost of the lamp. The lamp is more costly because it requires a ballast to regulate the flow of current through the lamp.
How does a fluorescent lamp operate?
A fluorescent lamp operates by sending electrical current through a gas-filled tube containing mercury vapor. This current excites the mercury atoms, causing them to emit ultraviolet light. The ultraviolet light then interacts with the phosphor coating on the inside of the tube, causing it to glow and emit visible light.
What is the parts of fluorescent lamp and there functions?
A fluorescent lamp consists of a glass tube filled with mercury vapor and coated with phosphor. The tube is connected to electrodes at each end. When electricity is applied, the electrodes produce an arc, which excites the mercury vapor to produce ultraviolet light. The phosphor coating then converts the ultraviolet light into visible light.
What does turning on a fluorescent lamp create?
A plasma arc of argon gas and/or other ions, such as mercury vapour, depending on the gas mixture used in the lamp.
What is the terminology HPMV for a lamp?
HPMV stands for High Pressure Mercury Vapor, which refers to a type of lamp that produces light by exciting mercury vapor with electricity. These lamps are often used in outdoor lighting applications due to their high efficiency and long lifespan.
What is CFL mhl and hpmv lamps?
The abbreviations are CFL - Compact Fluorescent Lamp, MHL - Metal Halide Lamp, HPMV - High Pressure Mercury Vapor, and one more is HPS - High Pressure Sodium lamp
What is a similarity in the line spectrum of mercury and the spectrum of the fluorescent bulb?
A fluorescent lamp contain mercury so the identities of spectrum are normal.
If a fluorescent lamp is brokenwhat chemical can contaminate the surrounding environment?
A broken fluorescent lamp can release mercury vapor, which is a toxic chemical that can contaminate the surrounding environment. It is important to carefully clean up and dispose of broken fluorescent lamps to prevent exposure to mercury.
How bright is 950 lumens?
220 lumens is equal to a tungsten incandescent light bulb of 15 watts. Halogen lamp 20 watts. Fluorescent lamp 60 watts. LED lamp 60 watts. high pressure sodium vapour lamp 117 watts. Mercury vapour lamp 50 watts or 17.32 candle power
What are compact flourecent lamps?
A Compact Fluorescent Lamp (CFL) is type of energy-saving bulb made from a small glass tube which is filled with mercury vapour. It has a phosphorescent coating on the inside of the tube which glows...
What gase use in flurocent lamp?
Fluorescent lamps use a mixture of gases, including mercury vapor and argon, to produce light. When electricity passes through the gases, ultraviolet light is produced, which then interacts with the phosphor coating inside the lamp to create visible light.
If a fluorescent lamp is broken what chemical can contaminate the surrounding environment?
A broken fluorescent lamp can release mercury vapor, which is a toxic chemical that can contaminate the surrounding environment. Mercury exposure can be harmful to human health and the environment, so it's important to handle and dispose of broken fluorescent lamps properly.
Why are low pressure mercury-vapour lamps coated with phosphors?
Low-pressure mercury-vapour lamps are coated with phosphors to convert the ultraviolet light emitted by the mercury into visible light that is more useful for general lighting purposes. This process allows the lamp to produce a broader spectrum of light, making it more appealing and efficient for human vision.
What is the type of gas in an arc lamp?
The type of gas commonly used in an arc lamp is typically a noble gas such as xenon or mercury vapor. These gases are chosen for their ability to produce a bright and steady light when an electric current is passed through them in the lamp.
How can you tell if a streetlight is a sodium vapor lamp?
The light in Sodium Vapour lamp is from an atomic emission process whereas in Mercury Vapour Lamp it is, finally, from fluorescence emission. The mechanism of light emission in a sodium vapour lamp is simple and straight-forward. The filaments of the lamp sputter fast moving electrons, which hit the sodium atoms(vapour) causing the valence electrons of the sodium atoms to excite to higher energy levels and the electrons thus excited relax by emiting the characteristic monochromatic bright yellow light(589nm). The mechanism in mercury vapour lamp is more involved and sequential. The sputtered electrons from the filaments, after having been accelerated by high voltage, hit the mercury atoms. Here also, the excited electrons of mercury atomsrelax by emitting characteristic but ultravilot(254nm,invisible) light. The photons of this ultravilot light fall on the fluorescent layer on the inner walls of the tube and excite the molecular bonds of the fluorescent material to various electronic and vibrational energy states. Hence, the light from the mercury vapour lamp is white. The basic difference between the two is, the former works by electric discharge (passage of electricity through sodium vapours at high/low pressure) while the latter works through the combined effect of electric discharge through mercury vapours and fluorescence from phosphors (luminescent materials). Although sodium vapour lamps produce much higher light output (about 90 lumens/watt) they cannot be used in lighting applications where colour-rendering property is very crucial. This is because most of the light emitted from a sodium vapour lamp is concentrated in the yellow part of the visible spectrum (around 580-590 nm) On the other hand, a mercury vapour lamp is quite suitable for lighting applications. This is because, the mercury vapour lamp can feed almost the entire visible region (380-780 nm) of the human visual system. Conventional fluorescent lamps can also be called as low-pressure mercury discharge lamps. In this system, when electric discharge strikes mercury vapours held at low pressure ( a few mm of mercury) it produces a lot of ultravilot radiation dominantly at 254 nm inside the column of the discharge tube. This UV radiation when impinging on the white coating made of fluorescent materials coated inside the discharge column of the tube will generate white light(called daylight). Light output from a fluorescent lamp is moderate (60 lumens/watt) while the colour-rendering index is high. posat by Chinmoy kanjilal and Tushar dhara,research scientists,SMIT,Sikkim,India.
