A television camera is very different from an ordinary camera in many ways. In an ordinary camera, images are captured on film. A television camera, on the other hand, produces pictures as electrical signal.A picture tube or chip in the camera produces an electrical current called the video signal. This signal varies according to the amount of light in the image. In the case of colour TV, there may be two or three tubes. Special filters split the light into the three primary colours, red, green and blue. The camera thus produces three signals which are combined into a signal video signal that is transmitted.

When you sit before the television watching your favorite programme, can you imagine that when your grandfather was young he had no TV to entertain him? The first TV pictures were produced in 1924 by John Logie Baird, but the first TV programs came on air only in 1936, when the BBC started its service. At that time, very few people had television sets. The pictures were not in colour, but black and white, and the quality of the pictures was also not good. But none of this mattered, and people who owned TV sets were greatly

Nowadays, mobile phones are a common sight you see them on buses, trains, in offices, on roads… almost everywhere you look. They are very convenient because they allow you to make calls from just about anywhere. You don’t need wires for a mobile phone… why is that?A mobile phone is actually a radio—an extremely sophisticated radio, but a radio nonetheless. Mobile phones work using ‘cells’. Each cell has a base station at its centre. The base station sends and receives calls from your phone. Your phone communicates with the base station using radio waves. As you move from place to place, your calls are transmitted from the nearest base station

People send telegrams for birthdays, anniversaries and on festive days. Telegrams are also sent when a message has to reach someone very urgently. You must have also heard of people sending and receiving telexes. Do you know how they are different?To put it very simply, the telegraph uses electrical pulses to transmit and receive signals. It was invented by an American inventor called Samuel Morse in 1837. He used electrical current to produce a clicking sound. With each click, a pointed instrument would mark dots and dashes on a strip of paper. These dots and dashes formed a code that is known as the Morse code. Today of course, we get telegrams in the form of printed messages. However, you cannot send a telegram from your home or office. Neither can you receive a telegram directly. It has to be delivered to you.                                                 

        The telex was introduced much later in 1958. It is a system by which subscribers can use international carriers to send messages and data directly to other subscribers throughout the world. They do not have to go to a telegraph office, and can receive telexes directly if they have a telex machine in their office. Indian Air Force squadrons also have squadron flags or standards. They are also in sky blue, with lotus flower and gold Asoka leaves, and the squadron badge in the centre. Air Force officers also wear badges as part of their uniforms. These badges are worn on their headgear, collars, and shoulder patches

The ring-ring of the telephone is one of the most familiar sounds we hear every day. It lets you know that someone wants to talk to you.When your friend dials your number, his call is connected to your phone by the telephone exchange. Telephone calls used to be connected by hands with an operator asking the caller which number he wanted, and then plugging in the correct wire. Today, of course, computers do all this automatically

In a telephone, our speech is changed into electrical signals. These signals travel through wires, or optical cables that carry them in the form of light. The signals can also travel through the air as radio waves, using satellites or antennas. To make a call, you must dial a series of numbers on your telephone. Once the call is connected, the microphone and loudspeaker in the receiver of the phone allows users to talk to each other. The microphone in the mouthpiece produces electrical signals that travel through the wires, or as radio waves. The loudspeaker in the earpiece turns these signals into sounds again

Indeed it does! Computer language is, in fact, a language made up only of numbers.The names of some computer languages are BASIC, COBOL and FORTRAN. These languages teach a computer to perform different functions. The person who writes the instruction in a language that the computer can understand is called a programmer

People who ‘surf’ the internet use a lot of special symbols and terms. Some are needed for technical reasons. Others are used to make communication faster and more fun!Some commonly used terms are ‘surf’ which means casually looking through different site, and of course ‘www’ which means ‘world wide web’. In internet language short forms are accepted like ‘4’ for ‘for’ or ‘u’ for ‘you’

No. Instead it will heat the room. Under normal circumstances, the heat from inside the fridge is taken out by the compressor and let out in the air behind the fridge. As a result, the space inside is cooled. If the fridge is kept open in a closed room, the chillness coming out through the front door of the fridge is cancelled by the heated air coming from behind.

 Apart from this, in any electrical appliance, a part of the electricity supplied is wasted as heat because of the principles of thermodynamics. This heat will raise the temperature of air inside the room.