File Name: light emitting diode and their application .zip
Light emitting diodes, LEDs are used for many jobs. Not only are they used as panel indicators on everything from televisions, radios and other forms of domestic electronic and industrial equipment, but they are also replacing more traditional technologies for lighting applications.
The aim of these studies was mainly to investigate the effects of monochromatic LEDs applied singly on the in vitro plant growth and morphogenesis. Various morphological and physiological parameters are considered that influence the growth and development of plants in vitro under red LED light as compared to those under normal light. Upon exposure to LED, in vitro-raised plants have shown significant improvements in growth and morphogenesis. In particular, red and blue lights, either alone or in combination, have a significant influence on plant growth. The present study gives an overview of the fundamentals of LEDs and describes their effects on in vitro plant growth and morphogenesis and their future potentials.
Principles of Luminescence 2. Luminescence in organic semiconductors 3. Evolution of luminescent materials for OLEDs 4. OLED fabrication and characterization 5. Artificial lighting and the role of OLEDs 6.
A light-emitting diode LED is a semiconductor light source that emits light when current flows through it. Electrons in the semiconductor recombine with electron holes , releasing energy in the form of photons. The color of the light corresponding to the energy of the photons is determined by the energy required for electrons to cross the band gap of the semiconductor. Appearing as practical electronic components in , the earliest LEDs emitted low-intensity infrared IR light. The first visible-light LEDs were of low intensity and limited to red. Modern LEDs are available across the visible , ultraviolet UV , and infrared wavelengths, with high light output. Early LEDs were often used as indicator lamps, replacing small incandescent bulbs, and in seven-segment displays.
Since ancient times man has obtained light from various sources like sunrays, candles and lamps. In , Thomas Edison invented the incandescent light bulb. In the light bulb, an electric current is passed through a filament inside the bulb. When sufficient current is passed through the filament, it gets heated up and emits light. The light emitted by the filament is the result of electrical energy converted into heat energy which in turn changes into light energy.
The diode is the most used semiconductor device in electronics circuits. It is a two-terminal electrical check valve that allows the flow of current in one direction. They are mostly made up of silicon but germanium is also used. Usually, they are used for rectification. These characteristics are modified to form different types of diodes.
The Light-emitting diode is a two-lead semiconductor light source. In , Nick Holonyak has come up with the idea of a light-emitting diode, and he was working for the general electric company. The LED is a special type of diode and they have similar electrical characteristics to a PN junction diode. Hence the LED allows the flow of current in the forward direction and blocks the current in the reverse direction. The applications of LEDs used to make various electrical and electronic projects. In this article, we will discuss the working principle of the LED and its applications.
Войдите, - буркнул Нуматака. Массажистка быстро убрала руки из-под полотенца. В дверях появилась телефонистка и поклонилась: - Почтенный господин. - Слушаю. Телефонистка отвесила еще один поклон: - Я говорила с телефонной компанией. Звонок был сделан из страны с кодом один - из Соединенных Штатов. Нуматака удовлетворенно мотнул головой.
Сквозь клубящийся дым Сьюзан кое-как добралась до дверцы лифта, но тут же увидела, что индикатор вызова не горит. Она принялась нажимать кнопки безжизненной панели, затем, опустившись на колени, в отчаянии заколотила в дверь и тут же замерла. За дверью послышалось какое-то жужжание, словно кабина была на месте.