Saturday, May 18. 2019When do we use a modem?
Computers that are connected to a telephone line incorporate a device called a modem. It turns signals into a form that can be transmitted along the telephone line. The name ‘modem’ comes from the term Modulator-Demodulator. The device modulates, or changes, the digital signal from a computer into an analogue signal, which is the type of signal that travels along telephone lines. The modem decodes, or demodulates, the signals it receives back so they can be read by the computer. Some modems are ‘voiceband’; that means they enable digital terminal equipment to communicate over telephone channels, which are designed around the narrow bandwidth requirements of the human voice.
Picture Credit : Google Saturday, May 18. 2019When was the CN Tower built?
The CN Tower in Toronto, Canada is a communications and observation tower. This building was completed in 1976, and at that time was the world’s tallest free-standing structure. The 20th century saw an explosion in communications technology. The first radio broadcast was made almost at the beginning of the century, when Reginald A. Fessenden transmitted music and words in 1906. By the 1920s, radio provided a major form of entertainment for many people around the world. Then, in 1926, a Scottish engineer named John Baird developed the first successful television set.
Picture Credit : Google Saturday, May 18. 2019When was the telescope invented?
Galileo is credited with having developed telescopes for astronomical observation in 1609. While the largest of his telescopes was only about 120 cm long and had an objective diameter of 5 cm, it was equipped with an eyepiece that provided an upright image. Galileo used his modest apparatus to explore the valleys and mountains of the Moon, the phases of Venus, and the four largest satellites, which had never been systematically observed before. The reflecting telescope was developed in 1668 by Newton. He became the first person to use a telescope to see the moons orbiting the planet Jupiter. He also used his theories about gravity to show why the planets orbit the Sun.
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