LEDs

LEDs are light emitting diodes. A light-emitting diode or LED is a semiconductor light source. LEDs are used as indicator lamps in many devices, and are increasingly used for lighting. Introduced as a practical electronic component in 1962, early LEDs emitted low-intensity red light, but modern versions are available across the visible, ultraviolet and infrared wavelengths, with very high brightness.

According to encyclopedia, the LED was invented by four independent American research groups in 1962. But the latest edition of Nature photonics reveals that it was actually discovered by a little-known Russian genius around 40 years earlier by Oleg Vldimirovich Losev.

LEDs emit light when an electric current passes through them.LEDs must be connected the correct way round, the diagram may be labelled a or + for anode and k or - for cathode. The cathode is the short lead and there may be a slight flat on the body of round LEDs. If you can see inside the LED the cathode is the larger electrode. LEDs can be damaged by heat when soldering, but the risk is small unless you are very slow. No special precautions are needed for soldering most LEDs.

LEDs do dozens of different jobs and are found in all kinds of devices, for example numbers on digital clocks transmit information from remote controls, light up watches and tell when appliances are turned on. Collected together, they can form images on a jumbo television screen or illuminate a traffic light.

LEDs are just tiny light bulbs that fit easily into an electrical circuit. But unlike ordinary incandescent bulbs, they don't have a filament that will burn out, and they don't get especially hot. They are illuminated solely by the movement of electrons in a semiconductor material, and they last just as long as a standard transistor. LEDs are thus more energy efficient and less expensive to use than the traditional incandescent bulbs which in turn helps in environmental sustainability.

Greenhouse Gases

Greenhouse gases are chemical compounds that are found in the Earth’s atmosphere. These gases allow sunlight to enter the atmosphere freely. When sunlight strikes the Earth’s surface, some of it is reflected back towards space as infrared radiation (heat). Greenhouse gases absorb this infrared radiation and trap the heat in the atmosphere. Over time, the amount of energy sent from the sun to the Earth’s surface should be about the same as the amount of energy radiated back into space, leaving the temperature of the Earth’s surface roughly constant. This process is the fundamental cause of the greenhouse effect. It is named this way because of a similar effect produced by the glass panes of a greenhouse. The primary greenhouse gases in the Earth's atmosphere are water vapour, carbon dioxide, methane, nitrous oxide, and ozone. In the Solar System, the atmospheres of Venus, Mars, and Titan also contain gases that cause greenhouse effects. Greenhouse gases greatly affect the temperature of the Earth; without them, Earth's surface would be on average about 33 °C (59 °F) colder than at present.

The Industrial revolution has substantially increased the levels of carbon dioxide in the atmosphere through the burning of fossil fuels. Greenhouse gases are also accumulating in Earth’s atmosphere as a result of human activities, causing surface air temperatures and sub-surface ocean temperatures to rise.

The impact of Green House Gases on the global climate since the Industrial Revolution has been complex. Though emissions of greenhouse gases, like carbon dioxide and methane have had a net warming effect, emissions of sulphate, aerosoles have had a net cooling effect.

Global Warming – A Burning Issue

Global warming relates to the increase in the average temperature of the Earth's surface which causes changes in climate. It is the most threatening situation in the present day. Global temperature and concentrations of carbon dioxide (one of the major greenhouse gases) have fluctuated on a cycle of hundreds of thousands of years as the Earth's position relative to the sun has varied. As a result, ice ages have come and gone. Now, global warming has become a critical case of concern because the rapid change in Green House Gases is changing the climate faster than some living things may be able to adapt. Also, a new and more unpredictable climate poses unique challenges to all life.

The impact of global warming is far greater than just increasing temperatures. It causes melting of Polar ice caps which will raise sea levels. There are 5,773,000 cubic miles of water in ice caps, glaciers, and permanent snow. According to the National Snow and Ice Data Center, if all glaciers melted today the seas would rise about 230 feet. Melting ice caps will throw the global ecosystem out of balance. The desalinization of the gulf current will imbalance ocean currents, which regulate temperatures. Temperature rises and changing landscapes in the artic circle will endanger several species of animals and only the most adaptable will survive. Global warming could snowball with the ice caps gone. Ice caps are white, and reflect sunlight, much of which is reflected back into space, further cooling Earth. If the ice caps melt, the only reflector is the ocean. Darker colors absorb sunlight, further warming the Earth. There is also increasing probability and intensity of droughts and heat waves. Although some areas of Earth will become wetter due to global warming, other areas will suffer serious droughts and heat waves.

Global warming also has serious economic consequences for all countries. Hurricanes cause billions of dollars in damage, diseases cost money to treat and control and conflicts exacerbate all of these.

The question now arises – How to deal with Global Warming? There is no one magic solution to the problem of global warming. Collective efforts and measures will contribute in tackling global warming. People all over the world have realized the seriousness of the problem and are taking appropriate steps to deal with this. The Kyoto Protocol is an example of this. The Kyoto Protocol is a protocol to the United Nations Framework Convention on Climate Change (UNFCCC or FCCC), aimed at fighting global warming.

Use of solar energy and energy saving products and LED products also contribute a lot in fighting global warming.