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Line 106: − − − − − − Radio − Many communication devices we know function through radio waves. Radio waves are electromagnetic waves. They carry energy through repeated propagation of electric and magnetic fields. Radio waves carry a certain amount of energy and can travel over large distances. When the wave reaches the destination, the receiver gets the amount of information. We cannot see radio waves but we can detect them by building receivers that can detect them. These are called as antennae. They scan the environment for radio signals and respond when they find a signal. They detect the radio signal by the effect of the changing electrical and magnetic fields. Frequency gives a measure of how fast the radio wave is being produced and depends on the source from where the radio waves start. Different radio waves come at different frequencies and we need to build transmitters that detect them. − How is sound transmitted using radio waves? − Sound is a pressure wave – when we produce a sound it travels by disturbing the air particles. If there is no medium, sound cannot travel. What happens when we hear something on a radio? Originally sound is produced and then it converted into radio waves. These waves are sent and received through instruments called antennae. When your radio antennae receives this radio wave, this is converted back into sound and is played. − Use of radio waves in astronomy − Radio waves are also produced by many celestial objects. By detecting the radio waves that travel through the atmosphere, it is possible to construct images of the astronomical objects. Radio waves can pass through dust and gas unlike light. Radio astronomy along with optical observation is allowing us to understand the universe better. − Lab exercises − For this we will need to open an application called PhET on the computer. You can find PhET under Applications> Education> Science. PhET is a software application that contains computer demonstrations of experiments and activities. These are called simulation. A simulation is like doing an experiment on the computer. We will learn more about simulations a little later when we learn about the use of computers in science. − The PhET simulation can also be found on the Internet at http://phet.colorado.edu/en/simulations/category/new. − When you open PhET you will see a page like the one shown below. − When we click on Play with sims – it will open simulations in various subjects. We will click on Physics and scroll down to the simulation on Waves on a String. − − When we want to open a simulation, we click on the green rectangle which says 'Run Now' − And this will start the simulation. − Exercise 1 : Observe the simulation 'Wave on a String' − You will see a picture like this. This is similar to a situation that you might have had where you tie a rope to one end and the other end is in your hand. − When you shake your hand, the rope will shake though it will be fixed at the other end. Similarly, if we move the wrench here, the rope (which is a collection of beads) will also move without being removed from the other end. − This simulation will allow you to move the string in different ways using the mouse and the various choices you have. Your teacher will explain what these various choices are. − − − − − − − − − Answer the following questions − 1. When you 'move' the wrench up and down, did the string move? How did it move? How did each of the beads move? − 2. When you look at the simulation, it looks like something is moving from one end to another. What is moving? − 3. Let us understand what happens when you move the string using the manual option. You can complete the table below. − − − Activity − What do you observe ? − Move the wrench upwards − − Move the wrench downwards − − Move the wrench upwards and downwards − − Are the beads in the string moving left to right; right to left, or up and down? What does this tell you about waves − − How fast does the string move when tension is high and when tension is low. Is there a difference and why? − − When you add damping how does the string move − − − 4. Let us understand what happens when you move the string using the oscillating option. You can complete the table below. You will see that there is a green rectangle on the top in which there are control buttons for amplitude, frequency and damping. We know what damping is. At the end of this simulation, you will be able to describe amplitude and frequency. − Increase and decrease amplitude − How does the wave look? How do the beads move? What changes in the beads when you change the amplitude? Do all the beads move in the same way? When you increase or decrease amplitude, what happens to the frequency − Increase and decrease frequency − How does the wave look? How do the beads move? What changes in the beads when you change the frequency? Do all the beads move in the same way? When you increase or decrease frequency, what happens to the amplitude? − Change the values of tension and damping − What do you observe is happening to the wave? What happens if the wave end is not fixed but loose? − Use the ruler to see how the beads move? − How far do the beads jump? Does it change? − − − − − − − − Exercise 2: Observe the simulation – Listen to a single source. − 1. Enable the audio-enabled and check the difference between the speaker and the listener. − − − − − − − − − − 2. − Why is this so? − 2.When you increase the frequency – what are the changes you see, hear? Do you come across these kinds of sounds (frequencies) anywhere. When you change the frequency, the nature of sound changes. There is a name for it. Ask your teacher. Where else does this aspect of sound come in? − − 3. When you change the amplitude, what happens? Based on what you hear, describe what you think is the meaning of amplitude. − − − − − − − − − − Telephone − Before the cell phone came, most of the long distance voice communication was through the regular telephone. This was based on the idea of travelling sound waves. They cause the mouthpiece to vibrate and this vibration is carried to the receiver at the other end. When a call came from one number, there will be an operator who sits at an office who will connect the call to another receiving number. Now this is different with automatic switches which connect the calls. − The transmission of the signals has also become different now with voice being converted into electrical signals. All these transmissions happen through physical cables. These cables are either made of copper or optical fibres. − − − − − − When you make a phone call, the voice signals from your phone get transmitted through these fibres to the nearest telephone exchange and through a series of switches sent to the receiver. Usually the first few numbers in our telephone number indicates the exchange information. − In the earlier days, long distance calls (outside of the local exchange) could only be made by booking a trunk call. The users had to 'book' or rent the line through which the call can be made and this used to be done manually by the telephone operators in the exchange. Now-a-days, with automatic switches, long distance calls can be made directly to any number, even outside the country. Line 180:
Line 111: − The telephone and the radio came together − And we call that the cell phone! We saw how a telephone works. We also saw what radio waves are and we have some idea of what frequencies mean. There are many frequencies available for the users to talk on. Any geographic area is divided into small plots, and in each area a fixed number of frequencies is used. Each of these areas are called cells. It is possible to make and receive calls when there is a cell phone tower near your area for receiving and sending that frequency. Now do you understand what we mean when we say 'my cell phone has no coverage here? − It is because of this also that cell phones sometimes do not work inside buildings when the radio signals are disturbed. Just like an exchange for regular telephone calls, there is a mobile switching that allows you to make calls even when you move from one cell to another! − Satellites for communication − A satellite is a moon, planet or a machine that orbits a planet or a star. The Earth and the Moon are examples of satellites of the sun and earth respectively. They are natural satellites. But there are also many man-made objects that are orbiting the Earth. These satellites are used to take pictures of the Earth, help in communication and also help in studying about the universe. − Weather satellites are those used for monitoring the changing conditions on the Earth's surface and atmosphere. − They take pictures of the Earth at various points and use this to forecast changes in weather, changes in the Earth's surface and forests.
ICT student textbook/Science Technology and Society (view source)
Revision as of 05:01, 10 October 2016
, 05:01, 10 October 2016no edit summary
=Information and communication technologies (ICTs)=
=Information and communication technologies (ICTs)=
Information is not new for human beings; communication has been known since the time human beings lived in caves. Thus ICT are as old as human beings themselves; human beings needed to communicate with one another, beginning with symbolic (non verbal) ways, before language was invented. The language we speak could be seen as first 'ICT', it enabled (oral) communication amongst human beings. Writing and script was the next technological advancement - around 5000 years ago - which enabled information could be created and communicated at different times and in a different place. Oral communication does not have this benefit, Writing also enabled easier recording of human history and thus the invention of script was a landmark in the history of ICTs. Next came printing which made it possible replicate writing. The invention of radio and television was the next advancement in ICT as it became possible for more and more people to access information. Thus, the technology for information creation and communication has been changing, connected with the advancements in scientific knowledge.
Information is not new for human beings; communication has been known since the time human beings lived in caves. Thus ICT are as old as human beings themselves; human beings needed to communicate with one another, beginning with symbolic (non verbal) ways, before language was invented. The language we speak could be seen as first 'ICT', it enabled (oral) communication amongst human beings. Writing and script was the next technological advancement - around 5000 years ago - which enabled information could be created and communicated at different times and in a different place. Oral communication does not have this benefit, Writing also enabled easier recording of human history and thus the invention of script was a landmark in the history of ICTs. Next came printing which made it possible replicate writing. The invention of radio and television was the next advancement in ICT as it became possible for more and more people to access information.
Thus, the technology for information creation and communication has been changing, connected with the advancements in scientific knowledge. Changes happened in the way computing evolved and changes happened in the way communication technology evolved, each impacting the other to produce the ICT environment we are now in; and which is still changing rapidly.
{|class="wikitable"
{|class="wikitable"
|Growth of ICT can be seen to be broadly in terms of 4 ages - premechanical, mechanical, electromechanical and electronic age. While technology for information creation, storage and processing has been developing continuously, one important development which changed the course of technology is the development of digital technologies in the electronic area. Whereas during the electromechanical area, information was stored largely stored in analog formats. During the electronic age, information was stored in analog and digital formats.
|Growth of ICT can be seen to be broadly in terms of 4 ages - premechanical, mechanical, electromechanical and electronic age. While technology for information creation, storage and processing has been developing continuously, one important development which changed the course of technology is the development of digital technologies in the electronic area. Whereas during the electromechanical area, information was stored largely stored in analog formats. During the electronic age, information was stored in analog and digital formats.
|}
|}
=Analog and digital technologies=
==Impact on computing and development of computers==
{|class="wikitable"
{|class="wikitable"
|-
|-
|An important breakthrough came when the binary system was invented. In the binary system information can in a series of "0"s and "1"s thus allowing information to be accessed through only a combination of "1"s and "0"s. This allowed information to be communicated in discrete bits which could be combined and recombined. Such a computer which uses "0"s and "1"s to perform computations a digital computer. What makes our society now different from ever before is the presence of digital technologies. Combined with the development of new methods of designing circuits like transistors and micro chips, it became possible to design computers which performed computations using digital methods. This improved the reliability and ease of computations significantly over the analog machines. The digital electronics changed operations in many applications including manufacturing, however the impact on ICT has been almost revolutionary. This has led to the growth of computers as we know it - from large clunky computers to the computer on your desktop to the laptop and now the smart phone. See the slideshow here for a glimpse of how the digital technology revolutionized history of computing.
|An important breakthrough came when the binary system was invented. In the binary system information can in a series of "0"s and "1"s thus allowing information to be accessed through only a combination of "1"s and "0"s. This allowed information to be communicated in discrete bits which could be combined and recombined. Such a computer which uses "0"s and "1"s to perform computations a digital computer. What makes our society now different from ever before is the presence of digital technologies. Combined with the development of new methods of designing circuits like transistors and micro chips, it became possible to design computers which performed computations using digital methods. This improved the reliability and ease of computations significantly over the analog machines. The digital electronics changed operations in many applications including manufacturing, however the impact on ICT has been almost revolutionary. This has led to the growth of computers as we know it - from large clunky computers to the computer on your desktop to the laptop and now the smart phone. See the slideshow here for a glimpse of how the digital technology revolutionized history of computing.
|}
|}
==Impact on communication technologies==
What is the word that comes to your mind when you say communication? The phone, precisely the cell phone. We will now look at how the communication technologies evolved.
===Radio communication===
The earliest electronic communication devices functioned using radio technology. Many communication devices we know today also function through radio waves. Radio waves are electromagnetic waves. They carry energy through repeated propagation of electric and magnetic fields. Radio waves carry a certain amount of energy and can travel over large distances. When the wave reaches the destination, the receiver gets the amount of information. We cannot see radio waves but we can detect them by building receivers that can detect them. These are called as antennae. They scan the environment for radio signals and respond when they find a signal. They detect the radio signal by the effect of the changing electrical and magnetic fields. Frequency gives a measure of how fast the radio wave is being produced and depends on the source from where the radio waves start. Different radio waves come at different frequencies and we need to build transmitters that detect them. Sound is a pressure wave – when we produce a sound it travels by disturbing the air particles. If there is no medium, sound cannot travel. What happens when we hear something on a radio? Originally sound is produced and then it converted into radio waves. These waves are sent and received through instruments called antennae. When your radio antennae receives this radio wave, this is converted back into sound and is played. <br>
'''Use of radio waves in astronomy''' : Radio waves are also produced by many celestial objects. By detecting the radio waves that travel through the atmosphere, it is possible to construct images of the astronomical objects. Radio waves can pass through dust and gas unlike light. Radio astronomy along with optical observation is allowing us to understand the universe better.
===Telephone===
Before the cell phone came, most of the long distance voice communication was through the regular telephone. This was based on the idea of travelling sound waves. They cause the mouthpiece to vibrate and this vibration is carried to the receiver at the other end. When a call came from one number, there will be an operator who sits at an office who will connect the call to another receiving number. Now this is different with automatic switches which connect the calls. The transmission of the signals has also become different now with voice being converted into electrical signals. All these transmissions happen through physical cables. These cables are either made of copper or optical fibres.
When you make a phone call, the voice signals from your phone get transmitted through these fibres to the nearest telephone exchange and through a series of switches sent to the receiver. Usually the first few numbers in our telephone number indicates the exchange information.
In the earlier days, long distance calls (outside of the local exchange) could only be made by booking a trunk call. The users had to 'book' or rent the line through which the call can be made and this used to be done manually by the telephone operators in the exchange. Now-a-days, with automatic switches, long distance calls can be made directly to any number, even outside the country.
The telephone and the radio came together
And we call that the cell phone! We saw how a telephone works. We also saw what radio waves are and we have some idea of what frequencies mean. There are many frequencies available for the users to talk on. Any geographic area is divided into small plots, and in each area a fixed number of frequencies is used. Each of these areas are called cells. It is possible to make and receive calls when there is a cell phone tower near your area for receiving and sending that frequency. Now do you understand what we mean when we say 'my cell phone has no coverage here?
It is because of this also that cell phones sometimes do not work inside buildings when the radio signals are disturbed. Just like an exchange for regular telephone calls, there is a mobile switching that allows you to make calls even when you move from one cell to another!
Satellites for communication
A satellite is a moon, planet or a machine that orbits a planet or a star. The Earth and the Moon are examples of satellites of the sun and earth respectively. They are natural satellites. But there are also many man-made objects that are orbiting the Earth. These satellites are used to take pictures of the Earth, help in communication and also help in studying about the universe.
Weather satellites are those used for monitoring the changing conditions on the Earth's surface and atmosphere.
They take pictures of the Earth at various points and use this to forecast changes in weather, changes in the Earth's surface and forests.
==Cell phones==
==Cell phones==
Lab exercises
Lab exercises
With the help of your teacher, look at the following websites:
With the help of your teacher, look at the following websites: