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What is Television?

A television (also known as TV, telly or tube) is a machine with a screen. Televisions receive broadcast signals and turn them into pictures and sound. The word "television" comes from the words tele and vision. Older TVs had a large cathode ray tube in a large wooden frame and sat on the floor like furniture. Newer TVs are much lighter.

A TV can show pictures from many television networks. Computers and mobile devices also can be used for watching television programs.

Television became available in crude experimental forms in the late 1920s, but these did not sell to the public. After World War II, an improved form of black-and-white TV broadcasting became popular in the United States and Britain, and television sets became commonplace in homes, businesses, and institutions. In 2013, 79% of the world's households owned a television set.


History of Television:-

In 1923, an American inventor called Charles Jenkins used the disk idea of Nipkow to invent the first ever practical mechanical television system. By 1931, his Radiovisor Model 100 was being sold in a complete kit as a mechanical television.

In 1926, just a little after Jenkins, a British inventor known as John Logie Baird, was the first person to have succeeded in transmitting moving pictures through the mechanical disk system started by Nipkow. He also started the first ever TV studio.

From 1926 till 1931, the mechanical television system saw many innovations. Although the discoveries of these men in the department of mechanical television were very innovative, by 1934, all television systems had converted into the electronic system, which is what is being used even today.


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How work Television?

An antenna on your roof picks up radio waves from the transmitter. With satellite TV, the signals come from a satellite dish mounted on your wall or roof. With cable TV, the signal comes to you via an underground fibre-optic cable.

The incoming signal feeds into the antenna socket on the back of the TV.

The incoming signal is carrying picture and sound for more than one program. An electronic circuit inside the TV selects only the station you want to watch and splits the signal for this station into separate audio and video information, passing each to a separate circuit for further processing.

The electron gun circuit splits the video part of the signal into separate red, blue, and green signals to drive the three electron guns.

The circuit fires three electron guns (one red, one blue, and one green) down a cathode-ray tube, like a fat glass bottle from which the air has been removed.

The electron beams pass through a ring of electromagnets. Electrons can be steered by magnets because they have a negative electrical charge. The electromagnets steer the electron beams so they sweep back and forth across the screen, line by line.

The electron beams pass through a grid of holes called a mask, which directs them so they hit exact places on the TV screen. Where the beams hit the phosphors on the screen, they make red, blue, or green dots. Elsewhere, the screen remains dark. The pattern of red, blue, and green dots builds up a coloured picture very quickly.

Meanwhile, audio information from the incoming signal passes to a separate audio circuit.

The audio circuit drives the loudspeaker so they recreate the sound exactly in time with the moving picture.


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Effects of television on human health:-

Interesting far more than their studies or other work more important, like the Cartoon channels. These characters are lovable but if viewed for long durations, disturb the concentrating power of children, in their studies. Most of the movies do not depict a true picture of our society which has its adverse impact on the child’s mind.

The light emitted from the television can prove to be too stimulating to our systems. This can reduce the levels of the brain hormone melatonin, which usually increase in the evening as light levels fall. This may affect the body's natural rhythm, keeping you awake longer and results in irregular sleep and extreme fatigue.

If your muscles stay inactive for too long, it can disrupt your metabolism leading to weight gain. Additionally, when you are watching TV, you tend to eat more and eat unhealthy foods due to advertising and other food cues on TV.

In the 1970s, a Professor named Werner Halperin suggested that the rapid changes of sounds and images on TV may affect the neurological system of a young child and can cause attention problems. 3-year-old child who watches two hours of TV per day is 20 percent more likely to have attention problems at age 7 than a child who watches no television and effect on eyesight.


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Effect of television on environment:-

Manufacturers use a greenhouse gas called nitrogen trifluoride to make the televisions, and as the sets have become more popular, annual production of the gas has risen to about 4,000 tonnes. As a driver of global warming, nitrogen trifluoride is 17,000 times more potent than carbon dioxide, yet no one knows how much of it is being released into the atmosphere by the industry, said Michael Prather, director of the environment institute at the University of California, Irvine. Prather's research reveals that production of the gas, which remains in the atmosphere for 550 years, is "exploding" and is expected to double by next year. Unlike common greenhouse gases such as carbon dioxide, sulphur hexafluoride (SF6) and perfluorocarbons (PFCs), emissions of the gas are not restricted by the Kyoto protocol or similar agreements. This is so harmful for us and over environment.


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