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CHAPTER IIREVIEW OF RELATED LITERATURE AND STUDIES

Related LiteratureLocalRadio was first developed through two different inventions which are the telegraph and telephone. These three technologies are closely related. It was first known as wireless telegraphy. It can be a device that can be either referred as an electronic appliance that we listen with or the content listened to. It all started because of radio waves which are electromagnetic waves that have the capacity to transmit music, speech, pictures and other data invisibly through air. There are many things that can transmit these things not only through these waves. Radio, microwaves, cordless phones, remote controlled toys and television broadcasts are some of the devices using electromagnetic waves.There are different ways on how to generate electricity. One of those ways is through using the suns energy or in other words, solar energy. Many people use solar energy to generate power for their everyday lives. This energy can be used for gadgets like cellphones, microwaves, household materials and more. It can be used to store energy so that they can limit the use of materials like batteries that are non-biodegradable and doesnt decay fast.Asolar powered radiois a portableradio receiverwhich is powered byphotovoltaic panels.It is primarily used in remote areas where access to power sources is limited. It was developed in the 1950s. It was capable of working without any source of electricity. It is very helpful for people. They can just store energy from the sun and dont buy batteries anymore. They dont require any plugs because they can be used without electricity. These can help people who are poor for they can listen to informative news without thinking of buying a lot of batteries.Asolar cellis an electrical device that converts the energy oflightdirectly intoelectricityby the photovoltaic effect. It is a form ofphotoelectric cellwhich, when exposed to light, can generate and support an electric current without being attached to any external voltage source.

ForeignEvery hour the sun beams onto Earth more than enough energy to satisfy global energy needs for an entire year. Solar energy is the technology used to harness the sun's energy and make it useable. Today, the technology produces less than one tenth of one percent of global energy demand. Many people are familiar with so-called photovoltaic cells, or solar panels, found on things like spacecraft, rooftops, and handheld calculators. The cells are made of semiconductor materials like those found in computer chips. When sunlight hits the cells, it knocks electrons loose from their atoms. As the electrons flow through the cell, they generate electricity. On a much larger scale, solar thermal power plants employ various techniques to concentrate the sun's energy as a heat source. The heat is then used to boil water to drive a steam turbine that generates electricity in much the same fashion as coal and nuclear power plants, supplying electricity for thousands of people. In one technique, long troughs of U-shaped mirrors focus sunlight on a pipe of oil that runs through the middle. The hot oil then boils water for electricity generation. Another technique uses moveable mirrors to focus the sun's rays on a collector tower, where a receiver sits. Molten salt flowing through the receiver is heated to run a generator. Other solar technologies are passive. For example, big windows placed on the sunny side of a building allow sunlight to heat-absorbent materials on the floor and walls. These surfaces then release the heat at night to keep the building warm. Similarly, absorbent plates on a roof can heat liquid in tubes that supply a house with hot water. Solar energy is lauded as an inexhaustible fuel source that is pollution and often noise free. The technology is also versatile. For example, solar cells generate energy for far-out places like satellites in Earth orbit and cabins deep in the Rocky Mountains as easily as they can power downtown buildings and futuristic cars. But solar energy doesn't work at night without a storage device such as a battery, and cloudy weather can make the technology unreliable during the day. Solar technologies are also very expensive and require a lot of land area to collect the sun's energy at rates useful to lots of people. Despite the drawbacks, solar energy use has surged at about 20 percent a year over the past 15 years, thanks to rapidly falling prices and gains in efficiency. Japan, Germany, and the United States are major markets for solar cells. With tax incentives, solar electricity can often pay for itself in five to ten years.Solar energy, radiantlightandheatfrom thesun, is harnessed using a range of ever-evolving technologies such assolar heating,solar photovoltaic,solar thermal electricity,solar architectureandartificial photosynthesis. Solar technologies are broadly characterized as eitherpassive solaroractive solardepending on the way they capture, convert and distribute solar energy. Active solar techniques include the use of photovoltaic panels andsolar thermalcollectors to harness the energy. Passive solar techniques include orienting a building to the Sun, selecting materials with favorablethermal massor light dispersing properties, and designing spaces thatnaturally circulate air. In 2011, theInternational Energy Agencysaid that "the development of affordable, inexhaustible and clean solar energy technologies will have huge longer-term benefits. It will increase countries energy security through reliance on an indigenous, inexhaustible and mostly import-independent resource which can be a way to enhancesustainability, reduce pollution, lower the costs of mitigating climate change, and keepfossil fuelprices lower than otherwise. These advantages are global. Hence the additional costs of the incentives for early deployment should be considered learning investments; they must be wisely spent and need to be widely shared".

Related StudiesLocalSolar powered flashlightsor can be also called as solar powered torches are flashlights that are powered bysolar energystored in rechargeablebatteries. Most of these flashlights uselight-emitting diodeslampssince they have lower energy consumption compared toincandescent light bulbs. Solar powered flashlights vary in features and capabilities. A typical solar flashlight can give useful levels of illumination on objects up to 50 meters away, and beam may be visible for much longer distances. The solar cells used for battery charging have an indefinite life expectancy. A solar powered flashlight may give several hours of light after being charged during the day.These flashlights may be designed to be impact resistant, weatherproof, and to float. Other models include features such as asolar cell phone charger,an AM/FM radio, or a siren to call for help in an emergency. Some models include a hand crank dynamo for charging at night.An experimental solar flashlight the size of a credit card features a white LED powered by 16 solar cells. Solar powered lights need not be manually recharged as in the case of conventional battery operated flashlights.Pollution from discarded batteries used in normal flashlights is eliminated.Solar powered flashlights can be used in remote locations where it is impossible to find any source of electricity except for solar power. A built-in solar cell array in a hand-held product has a very small capacity. The light output and run time of the solar flashlight are limited by the amount of energy that can be absorbed in a day. Flashlights are usually stored indoors or otherwise out of direct sunlight; consumers may find it inconvenient to remember to place the flashlight in full sunlight for several hours before use. Rechargeable cells self-discharge, so unless the flashlight is stored in a sunny location, the light may not function in an emergency. Rechargeable cells have a finite charge/discharge cycle life, and when the cells wear out it may be difficult for the consumer to replace them. Some of these disadvantages can be mitigated by separating the solar cell array from the flashlight, but then the simplicity of automatic charging is lost. Solar powered flashlights have been distributed to countries where there is either no or erratic power supply, helping people feel safer leaving their homes at night, and giving children the opportunity to study after sunset. A dual purpose solar flashlight, which also functions as a lamp has helped families in such countries spend more time together, surgeries to be performed during power outages and people to travel in the dark under a halo of light.

ForeignGinkgo Solar Tree is a solar powered phone and tablet charger that uses the energy of the sun to charge any device connected to it. It is an environmental friendly source of power that can charge an Android smartphone or an iPhone in two hours. One of the main challenges in designing a solar powered charger is that it takes hours for it to charge a device. If a shorter time is needed then bigger solar panels are needed to absorb the suns energy. This is however not feasible in a desktop environment. The XD Design team has come up with a way to harness the maximum amount of solar energy without resulting to a bulky product. They did this by taking inspiration from the Gingko Leaf, which is where the name of the project was taken from. The design based on the Gingko leaf is not only visually friendly but it also very efficient in absorbing the suns power.

References:http://inventors.about.com/od/rstartinventions/a/radio_2.htmhttp://en.wikipedia.org/wiki/Solar-powered_radiohttp://environment.nationalgeographic.com/environment/global-warming/solar-power-profile/http://en.wikipedia.org/wiki/Solar_energyhttp://en.wikipedia.org/wiki/Solar_cellhttp://en.wikipedia.org/wiki/Solar-powered_flashlighthttp://thedroidguy.com/2013/09/ginkgo-solar-tree-solar-powered-mobile-device-charger/