Category Everyday Science

HOW DOES A TELEVISION SHOW PICTURES?

Television technology uses electric signals through cables or ultra-high frequency (UHF) radio waves to transmit pictures and sound to a television set, which acts as a receiver. The signals come into the television through a cable or an aerial. The picture signals are divided into three — one each for red, green and blue. In the television, there is an electron gun for each colour, which fires electron beams (also known as cathode rays) onto the screen. The screen is covered with chemicals called phosphors. The electron beams scan rapidly across the screen, causing tiny dots of phosphors to glow red, green and blue. Viewed with normal vision, from a distance, the dots blur into a full-colour picture.

Most people spend hours each day watching programming on their TV set, however, many people might wonder how in fact television works. There are many parts to this process and many technologies that are involved. Following are the most important processes and technologies involved in making television work.

Main Elements of the TV Process

There are many major elements that are required in order for TV to work. They usually include a video source, an audio source, a transmitter, a receiver, a display device, and a sound device.

Video Source

The video source is the image or program. It can be a TV show, news program, live feed or movie. Usually the video source has already been recorded by a camera.How TV Works?

Audio Source

Besides the video source, we also need the audio source. Practically all movies, TV shows and news programs have some sought of audio. Audio source can be in the form of mono, stereo or digitally processed to be later played back with surround sound.

Transmitter

The transmitter is necessary for broadcast television companies that broadcast a free signal to viewers in their area. The transmitter transmits both the video and audio signals over the air waves. Both audio and video signals are electrical in nature and are transformed into radio waves which can then be picked up by receivers (your TV set). A transmitter not only transmits one channels audio or video signal, but in most cases many different channels.

Receiver (TV set)

A receiver is usually integrated in your TV set and this receiver is able to grab radio waves (the transmitted signal) and process these radio waves back to audio and video electric signals that can now be played on your TV set.

Display Device

A display device is usually a TV set, but can also be just a monitor. The display device is able to receive electrical signals (usually sent from the receiver) and turn these electrical signals to a viewable image. Most standard TV sets incorporate a cathode ray tube (CRT), however new display devices can include LCD (liquid crystal display) and Plasma (gas charged display) display devices among others.

Sound Device

While most sound devices are built into your TV set in the form of speakers. Audio signals are obviously needed to match up with the video being shown to the viewer. Many newer TV sets have outputs to send the TV sound to high quality speakers that reproduce sound much better. Since audio signals can include surround sound technology, the TV set is able to send audio signals to the proper speakers located around your room.

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HOW CAN LENSES CHANGE OUR VIEW?

The way in which we see the world has been greatly influenced by photography. We are used to seeing printed images that we could never see with our naked eyes, either because they happen too fast, or because a special camera lens has allowed an extraordinary view to be taken.

Macro-photography is a way of photographing very small objects by using special macro lenses. Used for both still and moving pictures, macro-photography has transformed our knowledge of the way that living things, such as insects, behave.

Macro photography is extreme close-up photography, usually of very small subjects and living organisms like insects, in which the size of the subject in the photograph is greater than life size (though macro-photography technically refers to the art of making very large photographs). By the original definition, a macro photograph is one in which the size of the subject on the negative or image sensor is life size or greater. However, in some uses it refers to a finished photograph of a subject at greater than life size.

The ratio of the subject size on the film plane (or sensor plane) to the actual subject size is known as the reproduction ratio. Likewise, a macro lens is classically a lens capable of reproduction ratios of at least 1:1, although it often refers to any lens with a large reproduction ratio, despite rarely exceeding 1:1.

Apart from technical photography and film-based processes, where the size of the image on the negative or image sensor is the subject of discussion, the finished print or on-screen image more commonly lends a photograph its macro status. For example, when producing a 6×4 inch (15×10 cm) print using 35formet (36×24 mm) film or sensor, a life-size result is possible with a lens having only a 1:4 reproduction ratio.

Reproduction ratios much greater than 10:1 are considered to be photomicrography, often achieved with digital microscope (photomicrography should not be confused with microphotography, the art of making very small photographs, such as for microforms).

Due to advances in sensor technology, today’s small-sensor digital cameras can rival the macro capabilities of a DSLR with a “true” macro lens, despite having a lower reproduction ratio, making macro photography more widely accessible at a lower cost. In the digital age, a “true” macro photograph can be more practically defined as a photograph with a vertical subject height of 24 mm or less.

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HOW CAN PHOTOGRAPHS ARE MADE TO MOVE?

Moving pictures, or movies, do not really have moving images at all. They are simply a series of still photographs, shown rapidly one after the other. Our brains are not able to distinguish the individual images at that speed, so we see what appears to be a moving picture.

Film, also called movie or motion picture, is a visual art-form used to simulate experiences that communicate ideas, stories, perceptions, feelings, beauty or atmosphere, by the means of recorded or programmed moving images, along with sound (and more rarely) other sensory stimulations. The word “cinema”, short for cinematography, is often used to refer to filmmaking and the film industry, and to the art form that is the result of it.

The moving images of a film are created by photographing actual scenes with a motion-picture camera, by photographing drawings or miniature models using traditional animation techniques, by means of CGI and computer animation, or by a combination of some or all of these techniques, and other visual effects.

Traditionally, films were recorded onto celluloid film through a photochemical process and then shown through a movie projector onto a large screen. Contemporary films are often fully digital through the entire process of production, distribution, and exhibition, while films recorded in a photochemical form traditionally included an analogous optical soundtrack (a graphic recording of the spoken words, music and other sounds that accompany the images which runs along a portion of the film exclusively reserved for it, and is not projected).

The movie camera, film camera or cine-camera is a type of photographic camera which takes a rapid sequence of photographs on an image sensor or on a film. In contrast to a still camera, which captures a single snapshot at a time, the movie camera takes a series of images; each image constitutes a “frame”. This is accomplished through an intermittent mechanism. The frames are later played back in a movie projector at a specific speed, called the frame rate (number of frames per second). While viewing at a particular frame rate, a person’s eyes and brain merge the separate pictures to create the illusion of motion.

Since the 2000s, film-based movie cameras have been largely (but not completely) replaced by digital movie cameras.

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WHO INVENTED THE LOCOMOTIVE?

A Locomotive is an engine that can travel under its own power, not pulled by horses, for example. But we usually think of it as running on tracks, or tramways, as they were first called. In 1804, Richard Trevithick (1771-1833), an English inventor, designed a train to pull coal wagons in a Welsh colliery. Trevithick was convinced that steam engines had a great future and later travelled to Peru and Costa Rica, where he introduced steam engines into the silver mines.

In 1802, Richard Trevithick patented a “high pressure engine” and created the first steam-powered locomotive engine on rails.  Trevithick wrote on February 21, 1804, after the trial of his High Pressure Tram-Engine, that he “carry’d ten tons of Iron, five wagons, and 70 Men…above 9 miles…in 4 hours and 5 Mints.”  Though a ponderous-sounding journey, it was the first step toward an invention that would utterly change man’s relationship to time and space. 

George Stephenson and his son, Robert, built the first practical steam locomotive.  Stephenson built his “travelling engine” in 1814, which was used to haul coal at the Killingworth mine.  In 1829, the Stephenson built the famous locomotive Rocket, which used a multi-tube boiler, a practice that continued in successive generations of steam engines.  The Rocket won the competition at the Rain-hill Trials held to settle the question of whether it was best to move wagons along rails by fixed steam engines using a pulley system or by using locomotive steam engines. The Rocket won the £500 prize with its average speed of 13 miles per hour (without pulling a load, the Rocket attained speeds up to 29 miles per hour), beating out Braithwaite and Erickson’s Novelty and Timothy Hackworth’s Sans Pareil.  The Stephenson incorporated elements into their engines that were used in succeeding generations of steam engines.

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WHAT DO THE NUMBERS BEFORE STEAM TRAIN NAMES MEAN?

Steam locomotives are described by the arrangement of their leading, driving and trailing wheels. In fact, only the driving wheels are connected to the cylinders that provide the engine’s power. So a 2-8-2 has two leading wheels, eight driving wheels and two trailing wheels.

Under the Whyte notation for the classification of Steam locomotives, 2-8-2 represents the wheel arrangement of two leading wheels on one axle, usually in a leading truck, eight powered and coupled driving wheels on four axles and two trailing wheels on one axle, usually in a trailing truck. This configuration of steam locomotive is most often referred to as a Mikado, frequently shortened to Mike.

At times it was also referred to on some railroads in the United States of America as the McAdoo Mikado and, during the Second World War, the MacArthur.

The notation 2-8-2T indicates a tank locomotive of this wheel arrangement, the “T” suffix indicating a locomotive on which the water is carried in side-tanks mounted on the engine rather than in an attached tender.

The 2-8-2 wheel arrangement allowed the locomotive’s firebox to be placed behind instead of above the driving wheels, thereby allowing a larger firebox that could be both wide and deep. This supported a greater rate of combustion and thus a greater capacity for steam generation, allowing for more power at higher speeds. Allied with the larger driving wheel diameter which was possible when they did not impinge on the firebox, it meant that the 2-8-2 was capable of higher speeds than a 2-8-0 with a heavy train. These locomotives did not suffer from the imbalance of reciprocating parts as much as did the 2-6-2 or the 2-10-2, because the center of gravity was between the second and third drivers instead of above the centre driver.

The first 2-8-2 locomotive was built in 1884. It was originally named Calumet by Angus Sinclair, in reference to the 2-8-2 engines built for the Chicago & Calumet Terminal Railway (C&CT). However, this name did not take hold.

The wheel arrangement name “Mikado” originated from a group of Japanese type 9700 2-8-2 locomotives that were built by Baldwin Works for the 3 ft 6 in (1,067 mm) gauge Nippon Railway of Japan in 1897. In the 19th century, the Emperor of Japan was often referred to as “the Mikado” in English. Also, the Gilbert and Sullivan opera The Mikado had premiered in 1885 and achieved great popularity in both Britain and America.

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WHICH WAS THE WORLD’S FIRST PUBLIC RAILWAY?

The first public railway in the world to run a regular service was opened on 27 September 1825. It ran between Stockton and Darlington in the north of England. A steam train called The Locomotion pulled 34 wagons, some of which carried coal, while others were adapted to carry passengers. Both the locomotive and its track were built to the design of George Stephenson (1781-1848). Stephenson’s background was in mining engineering. Coal mines had long used tracks to move wagons of coal, and it was with steam engines for these wagons that Stephenson first experimented.

“The world’s first public railway to use steam locomotives, its first line connected collieries near Shildon with Stockton and Darlington… The movement of coal to ships rapidly became a lucrative business, and the line was soon extended to a new port and town at Middlesbrough. While coal waggons were hauled by steam locomotives from the start, passengers were carried in coaches drawn by horses until carriages hauled by steam locomotives were introduced in 1833″. 

One of the significant results of the success of the Stockton and Darlington project was the extent to which it gave support to plans for building a railway between Liverpool and Manchester.

 

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