Since the discovery of nearly two centuries ago, a light bulb that illuminates the earth continues to grow. The demands of energy-saving lamps trigger innovation to produce increasingly efficient harnessing energy. Its function is no longer illuminates the house or the street, but extends, including the cultivation of plants.
Endeavor Joseph Swann, England, and Thomas Alva Edison, United States, in the 1870s resulted in an incandescent light bulb. Although they did not invent the first electric lights, their efforts allow mass production.
Incandescent light coming from the flame filaments, thin wire of tungsten. When the lamp is turned on, an electric current heats the filament to a temperature of 2200 degrees celsius to incandescent filament. So that the heat is concentrated around the filament, tungsten bulb placed inside airtight.
"Because the light from the heating process, an electric current determines the stability of the flame of the lamp," said the lecturer of Physics Study Program ITB, Rahmat Hidayat, Saturday (10/11/2014). Power supply voltage goes down, the supply current is reduced, the lights dimmed. Did the opposite.
Heating temperature is not too high to make the yellow rays. Light intensity or brightness level of an incandescent bulb is only 15 lumens per watt. Consequently, to produce a brighter light electrical energy needs are great.
However, for any given level of current, more than 90 percent is converted into heat. Only 5 percent of the electricity is converted into light. It is clearly inefficient and wasteful electricity.
Heating continuous filament, said Grace, will erode the surface
tungsten wire until the cross section is reduced to the filament breaks and the light can not be used anymore. Easily create age breakdown filament lamp life of 1,000 hours or four months for the use of 8 hours per day.
fluorescent Lamp
The nature wasteful incandescent bulbs pushing scientists and engineers to search for a new more efficient light bulbs energy related. Thus was born the fluorescent lamp or fluorescent lamp in 1938.
These lights are most widely used in Indonesia, both tube (tubular lamp / TL) and the compact. Some people call because many fluorescent lights used on billboards or neon.
Indeed, two different lamp types. The process produces both the same light, through the excitation of electrons. However, the gas content of the different excited. Excitation in fluorescent lights only once, whereas fluorescent lights twice.
When the lamp electrified, at the end of the tube electrode fluorescent lamps emit free electrons. The electrons will ionize the argon gas in low pressure tube.
Electric currents create free electrons and argon ions to move quickly from one electrode to the other electrode. An electric current is also changing from a liquid mercury in a tube so gas. That process will make the particles move (electrons and ions) collide with mercury atoms. As a result, the electron excited mercury, down to a more stable energy level and releases energy in the form of photons or ultraviolet light.
Furthermore, ultraviolet light will excite the phosphorus atoms in the layer in the tube. Phosphorus that is what gives white tube. In the process it will produce further excitation light invisible to the eye appear white. "Variation of fluorescent lights can be set based on the composition of phosphorus," he said.
The process was no further excitation in fluorescent lights. The gas used was not only argon, but also neon and krypton. Neon produces a red light, while the other gases produce different colors.
Fluorescent lamp produces light intensity is better than an incandescent bulb, 67 lumens per watt. The conversion of ultraviolet light into visible light also generates heat that is lost to the environment, but fewer in number. The average age of light longer, 8500-10000 hours.
LED Lights
Although more efficient than incandescent bulbs, the existence of which is a heavy metal mercury in fluorescent lamps so new problems because of damage to the environment and harm the health. There are growing demands saving lamp remains. In addition, future lights must be applied more widely.
Born tech light-emitting diode lamps (light-emitting diode / LED). Research LED light started 1960 by producing a red and green LED lights. Only in the 1990s, blue LEDs are present. With the discovery of blue LEDs, white LEDs can be made.
Findings on a blue LED that makes the Japanese scientist Isamu Akasaki Hiroshi Amano, and Shuji Nakamura was awarded the Nobel Prize in Physics in 2014.
LED light source lighting comes from a semiconductor diode form of solid material and capable of flowing electric current. The energy released from the movement of electrons in semikondutor that will produce light.
When power is applied, the free electrons from the semiconductor-enriched negative free electrons flow to the positive part. At the same time, the electrons in the positive holes move toward the negative.
The movement of free electrons to an electron falls into a hole. As a result, the electron energy levels down to a more stable and release photons / light. The higher the photon energy is produced, the resulting light of the higher frequency or wavelength.
Therefore, the color of the LED lamp light obtained depend on the mix of materials making up the diode. For example, a mixture of aluminum, gallium, and arsenic will produce a red light. The combination of indium, gallium and nitride blue color.
Compared to the size of the plant and fluorescent incandescent light bulbs, LEDs are very small size, the extent of less than 1 square millimeter. "The bigger the LED, the arrangement of their atoms more easily damaged so that the electric properties is reduced," said Grace who is also researching the LED.
Therefore, to make a light bulb is generally composed several LEDs. The small size also allows the LED lights placed on a variety of electronic circuits for a variety of lighting.
Not only the house or street lighting, LED circuit is also used for lighting a variety of electronic devices, start remote control, screen, smart phone, up to a television. In fact, LEDs can also be a substitute for sunlight to grow plants in space.
More than 50 percent of the electrical energy to the LED is converted into light. It makes LEDs more efficient than fluorescent lamps, especially incandescent bulbs. Every 1 watt of electricity capable of producing 70-100 lumens of light intensity. It may take longer service life up to 50,000 hours.
Complicated production process makes the price of LED bulbs are still expensive. However, if the calculated total cost of the purchase and use of electricity, the use of LEDs remain cheaper.
In addition, LEDs are also susceptible to the high temperatures that would make it overheat and fail to operate. Therefore, LEDs need a steady electric current and installation of electrical circuits appropriately.
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