My Science School

You can say that wireless communication is communication that requires no wires! To put it more accurately, it is communication that takes place through the air, using radio waves or infrared light. There is no need for cables or telephone lines for wireless communication. Wireless communication systems use devices called transmitters to generate radio waves. A microphone or other device converts sound or other data into electrical impulses. The transmitters change the impulses into radio signals that can be sent across great distances. Radio receivers pick up these signals, and turn them back into the original sound or messages.Wireless communication has also become a part of our daily life. It is used in our radios, televisions, mobile phones, remote controls and security systems. Wireless communications are a rapidly growing segment of the communications industry, and have mind boggling applications for the future.

You must have heard of planes and ships being located by radar, but what exactly is radar? It is a scientific method to detect and locate moving or fixed objects by using radio waves. In fact, the full form of the word ‘radar’ is ‘radio detection and ranging’. Radar can detect the distance, height, direction and speed of objects that are much too far for us to see. It does this by sending radio waves towards an object, and receiving the waves that are reflected from an object. The time it takes for the reflected waves to return from an object tells us how far away it is. The direction from which the reflected waves return tells us where the object is located.Radar can find anything from tiny insects to huge mountains. It is extremely useful as it works at night too and is not affected by the weather. In fact, it is used by weather departments to make forecasts. Radar is used to control the movement of aircraft and ships, and even to catch your father if he is over speeding!

A ringing cell phone can be a nuisance to others in some places like a theatre or at important meetings. A pager is very useful then, because it alerts you that someone is trying to contact you by vibrating silently. How does a pager work? If you want to page your friend, you must first dial the number of his paging service provider. You will then be connected to a computerized terminal which instructs you to key in your telephone number, and then press the ‘star’ key on your phone to complete the message. The paging terminal routes the signal to a radio transmitter. If your friend’s pager is switched on, and within the radio transmitters range, it will recognize the coded signal sent by the radio transmitter. The pager then converts the signal into data, and alerts your friend with a beep or vibration. You number will be displayed on his pager, and he can then call you back whenever it is convenient to him.

You can walk into nearly any office today, big or small and you will find a fax machine. Connected to a normal phone line, a fax machine allows you to copy send and receive documents instantly. The word ‘fax’ is the short form for ‘facsimile’ which means ‘an exact copy’. The fax machine works like a combination of a telephone and photocopier. The user places the paper with a picture or message into the document feeder of the sending machine. He then dials the telephone number of the receiving fax machine.An optical scanner in the sending machine records the variations between light and dark areas of the document. These variations are recorded as dots arranged in a series of rows or columns. A photo-electric cell converts the dots into electronic impulses which are transmitted through telephone wires to the receiving machine.The receiving machine converts the electrical impulses back into a series of dots. The decoded signal is sent to the print mechanism of the receiving fax. A duplicate of the original picture or message appears like magic!

Our lives have been completely changed with the invention of the telephone. No one person can really be credited with inventing it, though Alexander Graham Bell is acknowledged as the father of the modern telephone. Simply described, the telephone is a system which converts sound, specifically the human voice, to electrical impulses of various frequencies. These electrical frequencies are then turned back to a tone that sounds like the original The foundation for today’s telephone was laid in 1831, when an Englishman Michael Faraday, proved that vibrations of metal could be converted to electrical impulses. A practical telephone was actually invented independently by two men working in the United States, Elisha Gray and Scottish – born Alexander Graham Bell. Incredibly, both men filed for a patent on their designs at the New York patent office on February 14, 1876, with Bell beating Gray by only two hours!According to the famous story, the first fully intelligible telephone call occurred on March 6, 1876, when Bell, in one room, called to his assistant in another room. ‘Come here, Watson, I want you.’ Watson heard the request through a receiver connected to the transmitter that Bell had designed.

        

 They do, in order to make their task easier. The angler fish, for example, has a fleshy growth dangling from its forehead in front of its jaws. This is a form of visual communication which deceives smaller fish into thinking that the growth is food. When the smaller fish attempt to take a bite of the growth... SNAP...the angler fish gobbles them up! 

 Those of you who have seen gulls near the beach would have heard them communicating by screeching at each other. In a colony of gulls, all the little chicks will be crying at once and a mother gulls learns to identify the call of her own chicks.However, gulls use body language a lot in order to communicate with each other. The position of the head, and the way it stands, signals a gull's intentions. An upright posture indicates that it is likely to attack. Sometimes, a gull will lower its head and pull at grass when it is feeling aggressive.

 Elephants have many ways of communicating with each other. They use the trunk, the ears, the tail, body language and naturally their voices too.The way an elephant holds its trunk tells other elephants whether it is going to attack or defend itself. Elephants also touch and smell each other with their trunks to find out where the other elephant has just been, what it ate and how it feels. Elephants are capable of cornmunicating through their senses and through smells. They express joy and excitement by flapping their ears. The sound of ears beating on the skin is picked up by other elephants as a message to get in touch. The elephant’s tail is used to probesorroundings which they cannot see.Elephants can communicate with each other over great distances using their voices and hearing. Fellow elephants who know each other with quiet rumbling or purring which reminds one of a running diesel engine. Calves bellow loudly for their mothers when they feel lost. Anxious, attacking and attacked elephants  It is also known that elephant’s converse over great distances using infrasound which are low frequency sounds that human beings cannot hear. So, the next time you see an elephant standing frozen, with its head raised and ears sticking out, don’t disturb it…it is listening to a message that you cannot hear!

Experiments conducted by scientists seem to prove that dolphins do have a sort of language of their own. Dolphins appear to communicate with each other using an assortment of squeaks, whistles, and clicks. It is thought that they are warning each other of danger or if Food is nearby, but we are not yet certain exactly what they are saying. Some scientists have also discovered that dolphins can be trained to understand quite complicated commands given to them.

When a honeybee finds a big garden of flowers brimming with honey, how does it let its friends know about it? It hurries back to the hive, and does a little dance!Honey bees communicate with each other by dancing. The purpose of the dance is to alert other bees where nectar and pollen are located. The dance explains direction and distance to  The honey bee performs two types of dances...the round dance and the waggle dance. The round dance is performed for food sources close to the colony and the waggle dance used for food sources that are far Other bees attending these dances somehow-no one knows exactly how- learn the distance, direction, and odour of the flower patch. Once they have this information, they too fly directly to the flower patch in search of pollen and nectar

If you have seen a peacock spread out its feathers and dance, you will agree that it is a magnificent sight. But have you ever thought why it does this? The reason is quite simple… it wants to attract the female of its species which is known as a peahen! Dancing by the peacock is also an act to impress the peahen in front of him

Pheromones are chemicals released by living organisms to send messages to individuals of the same species. Pheromones play an important role in ensuring the reproduction of a species. They also serve to warn other members of the species of danger, to mark out territory, and to indicate food  When an ant is disturbed, it releases a pheromone that can be detected by other ants several centimetres away, causing them to run about as they work to remedy the Certain ants, as they return to the nest with food, lay down a trail of pheromone. This trail attracts and guides other ants to the   Some pheromones are deposited with the urine or faeces of an animal to mark its territory and warn away intruders. This is why you see dogs urinating on lamp posts!

 

Most of the time, animals communicate with their own species. This is especially true of mating signals, since animals must be able to communicate with their own species to mate and reproduce. A male elephant seal, for example, will give a loud roar that tells female seals where to come ashore for breeding. Communication within the species is also important in the case of caring for the young. A mother gull must be able to recognize the calls of her own chicks so that she can find them in a thickly populated gull colony, and feed them.But communication also takes place between different species. This is especially true of species living in the same area. Recognizing the warnings given by another species can be very helpful in avoiding danger. In Africa, grazing animals pay close attention to the keen eared zebra. If a zebra suddenly starts running, the other animals know that an enemy is approaching, and will flee too.

Animals communicate with one another in different ways. The sounds made by an animal, its behaviour and the way it looks at another animal are three   important means of Taste and odour, electrical impulse and touch are also used to attract or drive away another animal. Sometimes an animal uses a combination of different mediums to get its messages across most effectively.

Smell is probably the most common basic means of animal communication. Even the most primitive animals react to odours given off by their own, or other species.Animals may use scents, to mark out territorial boundaries, to attract mates, to warn off intruders and predators or, in some cases, to attract prey. Animals of all kinds rely to a great extent on their hearing ability in order to succeed and survive, and this is called acoustic communication. Among mammals, generally speaking, small animals squeak, and large ones rumble. The acoustic communication signal most frequently heard by humans is, of course, bird song. The largest of all animals, the whales, appear to be experts in the art of communication by sound, with each whale of the same species having its own favourite ‘songs’ which it repeats at intervals.Visual signals may take the form of gestures and displays, facial grimaces, body posture or mimicry. Each species has its own way of using its facial expressions, body language, gestures and body markings to communicate effectively.At another level, animals may communicate a simple message through the art of mimicry. The markings on the wings of the peacock butterfly look like large eyes to frighten off its enemies. The same is true of the harmless hoverfly that resembles the wasp.