China's first electric light.
1882 at 7: 00 p.m. on July 26th, a generator in Shanghai started to turn and lit the 15 electric light. This is an important moment in the history of Shanghai civilization and a new era in the history of China electric lights. Since then, electric lights have been lit on the land of China.
Edit the working principle of this paragraph.
An electric lamp is a device that converts electric energy into light energy to provide lighting. Its working principle is: when the current passes through the filament (tungsten filament, melting point is more than 3000 degrees Celsius), heat is generated, and the spiral filament continuously accumulates heat, so that the temperature of the filament reaches more than 2000 degrees Celsius. When the filament is incandescent, it shines like hot iron. The higher the temperature of the filament, the brighter the light it emits. So it's called incandescent lamp.
From the point of view of energy conversion, when an electric lamp emits light, a lot of electric energy will be converted into heat energy, and only a small part can be converted into useful light energy.
The light emitted by electric lamps is full color light, but the proportion of each color light is determined by the luminescent substance (tungsten) and temperature. The imbalance of proportion leads to the color deviation of light, so the color of the object is not true enough under incandescent lamp. (i.e. low color rendering)
The reason why electric lights will turn black when used for a long time
The tungsten wire that glows in the electric lamp can remain stable at extremely high temperature, and it will not melt, but sublimate directly into gas. When the lights are turned off, the temperature drops, and the tungsten gas condenses into a solid again, covering the inner wall of the bulb. Because tungsten is a black solid, incandescent lamps will turn black after long use.
Electric lamps have a long life. Generally, after blackening, their life will not be long. Black light bulbs will affect the lighting quality and are unsightly. Therefore, it is best to replace it as soon as possible, especially in conspicuous places, which need good lighting to avoid the sudden failure of light bulbs without spare bulbs, which will affect normal lighting's life and cause various inconveniences.
The life of the lamp is related to the temperature of the filament, because the higher the temperature, the easier it is for the filament to sublimate (tungsten directly becomes tungsten gas). Tungsten wire sublimates and becomes thinner, and it is easy to burn out after being electrified, thus ending the life of the lamp. Therefore, the greater the power (wattage) of an electric lamp, the shorter its life.
Edit this paragraph to invent the electric light.
Before the advent of electric light, candles, kerosene lamps or gas lamps were widely used as lighting tools. Because this kind of lamp burns kerosene or gas, the black smoke is very thick, the smell is pungent, and it is inconvenient to add fuel, so the lampshade is often scrubbed. More importantly, this kind of lamp is easy to cause fire, which will lead to great disaster. For many years, many scientists have tried their best to invent a safe and convenient electric light.
The lamp is a great invention for human beings to conquer the night. It was the American inventor Edison who really invented the electric light to make it shine. He is the child of a railway worker. He dropped out of school before finishing primary school and made a living by selling newspapers on the train. Edison is an extremely diligent man. He likes to do all kinds of experiments and make many exquisite machines. He is particularly interested in electrical appliances. Ever since Faraday invented the electric motor, Edison was determined to make electric lights and bring light to mankind.
Edison made a detailed test plan after carefully summarizing the previous failure experience in manufacturing electric lamps, which was divided into two aspects: one was to classify and test 1600 different heat-resistant materials; The second is to improve the vacuum pumping equipment to make the bulb have a high vacuum degree. He also studied the new generator and circuit shunt system.
/kloc-At the beginning of the 9th century, a British chemist made the world's first arc lamp with 2000 batteries and two carbon rods. But this kind of lamp is too strong and can only be installed in streets or squares, which is not used by ordinary families. Numerous scientists have racked their brains to make a cheap and durable household electric light.
1879101October 2 1 day, an American inventor finally lit the world's first electric lamp with practical value after long-term repeated experiments. Since then, the inventor's name, like the electric light he invented, has entered thousands of households. He is Edison, who is praised as "the king of invention" by later generations.
1847 In February, Edison was born in Milan, Ohio, USA. He has only studied in school for three months in his life, but he is studious and diligent in thinking. His invention has created many achievements 1000, such as electric light, phonograph and movie camera, and made great contributions to mankind.
When Edison 12 years old, he was addicted to scientific experiments. After his tireless self-study and experiments, at the age of 16, he invented an automatic telegraph that sends signals every hour. Later, the automatic counting machine, the first practical typewriter, double and quadruple telegrams, automatic telephones and phonographs were invented one after another. Edison was not satisfied with these inventions. 1in September, 878, Edison decided to attack the fortress of electric lighting. He read a lot of books about electric lighting and made up his mind to make cheap, durable, safe and convenient electric lights.
He started the experiment with an incandescent lamp. Put a small piece of heat-resistant thing in a glass bubble, and when the current burns it to a white-hot level, it will give off heat and glow. His first thought was charcoal, so he put a small piece of charcoal wire into a glass bubble, and the glass bubble broke as soon as it was electrified.
"What is the reason?" Edison picked up the carbon wire broken in two and looked at the glass bubble again. After a long time, he suddenly remembered: "Oh, maybe it's because there is air in it. The oxygen in the air helps the carbon wire burn and makes it break immediately!" " So he used his own hand-made air extractor to extract the air from the glass bubble as much as possible. Once it is electrified, it will not go out immediately. But eight minutes later, the light went out.
In any case, Edison finally found that the vacuum state is very important for incandescent lamps, and the key is carbon filament, which is the key to the problem.
So what kind of heat-resistant materials should we choose?
Edison thought about it. Platinum has the highest melting point and strong heat resistance! So Edison and his assistants tried platinum several times, but this kind of platinum with higher melting point prolonged the luminous time of the electric lamp a lot, but it was still not ideal to turn it off automatically and then glow from time to time.
Undaunted, Edison continued his experimental work. He tried various rare metals such as barium, titanium and indium, and the results were not very satisfactory.
After a while, Edison made a summary of the previous experimental work and wrote down all kinds of heat-resistant materials he could think of, totaling 1600.
Next, he and his assistants began to test 1600 kinds of heat-resistant materials in different categories. You can try it, and platinum is the most suitable one. Due to the improved air extraction method, the vacuum degree in the glass bulb is higher and the life of the lamp is extended to 2 hours. But this kind of platinum lamp is too expensive. Who wants to spend so much money on a light that can only last for two hours?
The experimental work fell into a trough, and Edison was very upset. In a cold winter, Edison sat by the fire and looked at the burning coals. He couldn't help saying to himself, "Charcoal, Charcoal ..."
Charcoal bars have been tried. What should I do? Edison felt hot all over, so he pulled down the scarf around his neck. Seeing this scarf made of cotton yarn, Edison suddenly had an idea in his mind: Yes! Cotton yarn has better fibers than wood. Can you use this material?
He quickly tore off a cotton yarn from his scarf and baked it on the fire for a long time. Cotton yarn turned into charred charcoal. He carefully put this carbon wire into the glass bubble, and after testing, the effect is really good.
Edison was very happy, and then he made a lot of carbon filaments from cotton yarn and did many experiments in succession. The life of the light bulb was extended by 13 hours, and then it reached 45 hours.
As soon as the news spread, it caused a sensation all over the world. The share price of London Gas plunged, and the gas industry was in chaos. People have a hunch that lighting gas lamps will soon become history, and the future will be the era of electro-optics.
Everyone congratulated Edison, but Edison didn't look happy at all. He shook his head and said, "No, we have to find other materials!" " "
"Why, it's been 45 hours?" The assistant asked in surprise. "no! I hope to open 1000 hours, preferably 16000 hours! " Edison replied.
As we all know, it is good to shine for more than 1000 hours, but what materials can we find?
Edison knew what he was doing. According to the nature of cotton yarn, he decided to look for new materials from plant fibers.
So, the marathon experiment began again. Edison experimented with all kinds of plant materials he could find, even horse mane, human hair and beard were used for filament experiments. Finally, Edison chose bamboo as a plant. Before the experiment, he took out a bamboo and observed it with a microscope. He jumped for joy. So, put the carbonized bamboo filament into the glass bulb, and after electrifying, the bamboo filament bulb lights continuously 1200 hours!
Edison finally breathed a sigh of relief, and his assistants congratulated him one after another, but he said seriously, "There are many bamboos in the world, and their structures are different. We should choose them carefully! "
Edison's scientific attitude of pursuing perfection deeply touched him, and his assistants volunteered to visit various places. After comparison, a kind of bamboo produced in Japan is the most suitable, so it is imported from Japan in large quantities. At the same time, Edison started a power plant and set up electric wires. Soon, the American people used this cheap and durable bamboo light bulb.
Bamboo filament lamp has been used for many years. Until 1906, Edison switched to tungsten wire, which improved the quality of the light bulb and has been used ever since.
When people turn on the electric light, they often think of this great inventor, who brought endless light to the darkness. From 65438 to 0979, the United States spent millions of dollars to hold a year-long commemorative event to commemorate the centenary of Edison's invention of the electric light.
The invention dispute edits this paragraph.
It is generally believed that the electric light was invented by Thomas Edison, an American. However, another American, Henry Goebbels, invented the reliable light bulb with the same principles and materials decades earlier than Edison, and many people made many contributions to the invention of the light bulb before Edison. 180 1 year, British chemist David electrified platinum wire to make it glow. 18 10, he also invented the electric candle, which was illuminated by an arc between two carbon rods. 1854, Henry Goebbels put a carbonized bamboo filament under a vacuum glass bottle to make it glow. Today, his invention seems to be the first incandescent lamp with practical value. The light bulb he tested at that time could last for 400 hours, but he didn't apply for the design patent in time.
1850, the Englishman Joseph Wilson Swan began to study electric lights. 1878, he obtained a British patent for a light bulb powered by carbon wire under vacuum, and started to set up a company in Britain to install electric lights in every household.
1874, two Canadian electrical technicians applied for a patent for electric lamps. They filled helium gas under the glass bubble, and the charged carbon rod would glow. But they didn't have enough financial resources to continue developing this invention, so they sold the patent to Edison at 1875.
Edison tried to improve the filament after buying the patent. 1879, he changed to carbon filament to make a light bulb, which successfully lasted 13 hours. By 1880, his carbonized bamboo filament bulb had been successfully maintained in the laboratory 1200 hours. But in Britain, Swan sued Edison for patent infringement and won. Edison's electric light company in England was forced to make Swan a partner. But later Swan sold his rights and patents to Edison. In America, Edison's patent has also been challenged. The United States Patent Office once ruled that his invention had a criminal record and was invalid. Finally, after years of litigation, Edison obtained the patent right of carbon filament incandescent lamp.
Edit this performance comparison
Most electric lamps convert 90% of the consumed energy into useless heat energy, and less than 10% of the energy becomes light. In contrast, fluorescent lamps (also known as tubes) are much more efficient, close to 40%, and produce only one-sixth of the heat of incandescent lamps with the same brightness. Therefore, in many places, especially shopping malls, buildings that need air conditioning in summer will use fluorescent lamps to save electricity. Small fluorescent lamps (energy-saving bulbs) combine fluorescent lamps with starting electronic equipment, and use the interface of standard bulbs to replace ordinary incandescent bulbs. For example, a 26-watt energy-saving light bulb emits 1 1W brightness and 15W heat. An incandescent bulb with the same brightness 1 1 watt consumes four times more power, reaching 100 watt; It releases more than six times the heat, reaching 90 watts.
Many household lamps are mainly ordinary lamps. Halogen bulbs have become more and more popular in recent years, especially when the light source needs to be concentrated, such as spotlights at home and headlights of cars. A good halogen bulb can achieve the efficiency of 15%. It uses more heat-resistant seasonable glass (the temperature of halogen lamp is very high, about 2 100 degrees) to replace the ordinary glass of electric lamp, and the halogen gas (iodine or bromine) of halogen lamp is filled into the bulb. Halogen and tungsten are decomposed and synthesized in the bulb by temperature difference, thus prolonging the life of filament. But timely glass can't isolate ultraviolet rays like ordinary glass. So if you are exposed to its ultraviolet rays for a long time, your skin will turn bronzed.
Edit the category and purpose of this paragraph.
Lighting electric light sources are generally divided into incandescent lamps, gas discharge lamps and other electric light sources. In the green lighting project, various light sources can be selected according to specific conditions.
First, incandescent lamp (incandescent lamp)
1. Ordinary incandescent lamps are commonly used incandescent bulbs.
Features: Good color rendering (Ra= 100), bright lights, continuous dimming, simple structure, low price, short service life and low light efficiency.
Uses: living room, living room, lobby, guest room, shop, restaurant, walkway, conference room, courtyard.
Uses: table lamp, ceiling lamp, wall lamp, bedside lamp, corridor lamp.
Second, halogen lamps (tungsten halogen lamps)
Inflatable incandescent lamp, the filling gas contains some halogen elements or halides. It has all the characteristics of ordinary lighting incandescent lamp, the light efficiency and service life are more than twice as long as those of ordinary lighting incandescent lamp, and the volume is small.
Uses: special lighting for conference rooms, exhibition halls, living rooms, commercial lighting, film and television stages, instruments, automobiles, airplanes, etc. 2. Gas discharge lamp 1. Low pressure discharge lamp (vapor) (1) fluorescent lamp.
3. Commonly known as fluorescent lamp
Features: high light efficiency, long life and good light color.
Fluorescent lamps are straight tube type, ring type and compact type. It is a widely used energy-saving lighting source.
Using straight fluorescent lamp instead of incandescent lamp can save electricity by 70~90% and prolong life by 5~ 10 times.
Upgrade the straight fluorescent lamp to save electricity15 ~ 50%;
Replacing incandescent lamp with compact fluorescent lamp can save electricity by 70~80% and prolong life by 5~ 10 times. (2) Low-pressure sodium (vapor) lamp.
Features: high luminous efficiency, long service life, high luminous flux retention rate, strong fog permeability, but poor color rendering.
Uses: Lighting for tunnels, ports, docks and mines.
4. (High Intensity Discharge Lamp)
High intensity gas discharge lamps include fluorescent high pressure mercury lamps, high pressure sodium lamps and metal halide lamps.
(1) fluorescent high-pressure mercury lamp
Features: Long service life and relatively low cost.
Uses: road lighting, indoor and outdoor industrial lighting, commercial lighting.
(2) High pressure sodium lamp
Features: long service life, high light efficiency and strong fog permeability.
Uses: road lighting, floodlighting, square lighting, industrial lighting, etc.
(3) Metal halide lamps
Features: long life, high luminous efficiency and good color rendering.
Uses: industrial lighting, urban lighting, engineering lighting, commercial lighting, stadium lighting and road lighting.
(4) ceramic metal halide lamp
Features: The performance is superior to that of general metal halide lamps.
Uses: Shopping mall, window, key display and commercial street lighting.
5。 High-frequency electrodeless lamp (electrodeless lamp)
Features: long service life (40000~80000 hours), no electrode, instant start and restart, no stroboscopic, good color rendering.
Uses: public buildings, shops, tunnels, pedestrian streets, high-pole street lamps, security lighting and other outdoor lighting.
6. Halogen bulbs
Halogen lamp, also known as tungsten halogen lamp, is a kind of incandescent lamp. The principle is to inject halogen gas such as iodine or bromine into the bulb. At high temperature, the evaporated tungsten wire reacts chemically with halogen, and the evaporated tungsten will solidify again on the tungsten wire to form a balanced cycle to avoid premature fracture of the tungsten wire. Therefore, halogen bulbs last longer than incandescent lamps. In addition, halogen bulbs can work at a higher temperature than ordinary incandescent lamps, with higher brightness and efficiency. However, at this temperature, ordinary glass may soften. Therefore, halogen bulbs need to use timely glass with higher melting point. Because timely glass can't block ultraviolet rays, halogen bulbs usually need to use additional ultraviolet filters. If there is oil in the crystal glass on the halogen bulb, it will cause different temperatures on the glass and reduce the life of the bulb. Therefore, when replacing halogen bulbs, people should avoid touching the glass of the bulbs.
Cordless lamp
On June 10, 2007, researchers from Massachusetts Institute of Technology conducted the experiment of "cordless light bulb". The research team led by Sol Jasik used two copper wire coils as vibrators, and one coil was connected to a power supply as a transmitter. The other is connected to a desk lamp and acts as a receiver. As a result, they successfully lit a 60-watt electric light at a distance of 2. 13 meters from the transmitter. Moreover, experiments show that wireless power transmission technology is harmless to human beings, because electromagnetic field only affects objects that can vibrate with it.
Led light
Structure and luminous principle of LED
Fifty years ago, people knew the basic knowledge that semiconductor materials can emit light. The first commercial diode was produced in 1960. LED is the abbreviation of English light emitting diode. Its basic structure is a piece of electroluminescent semiconductor material, which is put on the shelf with leads and then sealed with epoxy resin to protect the internal core wire, so the led has good seismic performance.
The LED structure diagram is shown in the following figure.
The core of LED is a wafer composed of P-type semiconductor and N-type semiconductor. There is a transition layer between P-type semiconductor and N-type semiconductor, which is called pn junction. In the PN junction of some semiconductor materials, when the injected minority carriers recombine with the majority carriers, the excess energy will be released in the form of light, thus directly converting electric energy into light energy. When reverse voltage is applied to PN junction, minority carriers are difficult to inject, so they do not emit light. This kind of diode made by injection electroluminescence principle is called light emitting diode, commonly known as led. When working in the forward direction (that is, DC voltage is applied at both ends), when the current flows from the anode of the LED to the cathode, the semiconductor crystal emits different colors of light from ultraviolet to infrared, and the intensity of light is related to the current.
Characteristics of LED light source
1. voltage: LED uses low-voltage power supply, the power supply voltage is between 6-24V, which varies according to different products, so it is safer than using high-voltage power supply, especially suitable for public places.
2. Efficiency: Compared with incandescent lamps with the same light efficiency, the energy consumption is reduced by 80%.
3. Applicability: Very small, each unit LED chip is 3-5mm square, so it can be made into devices with various shapes and is suitable for changing environments.
4. Stability: 654.38+100000 hours, and light attenuation is 50% of the initial value.
5. Response time: The response time of incandescent lamp is millisecond, and that of LED lamp is nanosecond.
6. Environmental pollution: no harmful metal mercury.
7. Color: the color can be changed by changing the current, and the energy band structure and band gap of the material can be easily adjusted by chemical modification of the light-emitting diode, so as to realize multicolor emission of red, yellow, green, blue and orange. For example, an LED that is red at low current can turn orange, yellow and finally green with the increase of current.
8. Price: led is more expensive. Compared with incandescent lamps, the price of several LEDs can be equivalent to the price of an incandescent lamp. Usually, each group of signal lamps needs to be composed of 300 ~ 500 diodes.
Edit this new invention of electric light.
"Gravity lamp" relies on gravity to generate electricity, and its brightness is equivalent to that of a 12 watt fluorescent lamp, so it has a long service life.
Clay Morton from Virginia, USA, received a master's degree from Virginia Tech last year. His research topic is a kind of lamp made of light-emitting diodes, named "Gravia". In fact, it is a cylinder made of acrylic material, and its height is slightly more than 4 feet (about 1.2 1 m). The luminous principle of this lamp is that the heavy objects on the lamp drive the rotor to rotate when it falls slowly, and the electric energy generated by the rotation will electrify the lamp and make it shine.
The luminous flux of this lamp is 600 to 800 lumens (equivalent to the brightness of 12 watt fluorescent lamp) for 4 hours. To turn on the lamp, the operator only needs to move the weight on the lamp from the bottom to the top and put it in the groove at the top. It only takes a few seconds for the weight to slowly descend, and the LED light will be on.
Clay Morton said that operating this light is certainly more troublesome than pressing the switch, but it is still acceptable and more interesting, just like winding a classical clock or leisurely making a delicious cup of coffee. Morton estimated that the service life of Gravia lamps can reach more than 200 years. At present, this lamp named "Gravia" has been applied for and patented.