| Line 65: |
Line 65: |
| | | | |
| | ===Telephone=== | | ===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. | + | 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 used to happen through physical cables. These cables were 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 cell phone=== |
| | + | 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. The cell phone is called a cell phone because it functions by dividing a geographical area into small plots or cells through which the transmission takes place. 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! |
| | | | |
| − | | + | Can you make a list of all the things a cell phone does? |
| − | | |
| − | 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==
| |
| − | You are right! The first word that comes to our mind is a cell phone. You may have seen many people carry a cell phone these days. Can you make a list of all the things a cell phone does?
| |
| | {|class="wikitable" | | {|class="wikitable" |
| | |- | | |- |
| Line 99: |
Line 83: |
| | One of the important parts of the cell phone is called the SIM card. The SIM card connects the phone to the network, your location. This helps the phone connect to a cell phone network and can also store phone numbers. It can be removed from one phone and put in any other cell phone. | | One of the important parts of the cell phone is called the SIM card. The SIM card connects the phone to the network, your location. This helps the phone connect to a cell phone network and can also store phone numbers. It can be removed from one phone and put in any other cell phone. |
| | |} | | |} |
| − | Lab exercises
| |
| − | 1. Draw a concept map of cell phone using Freemind. Your concept map can include all the features of a cell phone, charges on a cell phone, cell phone providers, etc.
| |
| − | 2. Ask your teacher to open a cell phone and identify all the parts on it.
| |
| − | Why is a cell phone called a cell phone?
| |
| − | We also call the cell phone a mobile. Why is it called mobile? We can use it to communicate when we are moving as it is not limited to a fixed location. A cell phone is like a radio. We will discuss below how a radio works. A cell phone is the telephone and radio combined! The cell phone is called a cell phone because it functions by dividing a geographical area into small plots or cells through which the transmission takes place. We will come back to this topic after we learn a little bit about radio.
| |
| | | | |
| − | | + | ===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. |
| − | | |
| − | | |
| − | Lab exercises
| |
| − | With the help of your teacher, look at the following websites:
| |
| − | http://www.nasa.gov/audience/forstudents/5-8/index.html
| |
| − | http://www.youtube.com/watch?v=E4k3kEA3pmo
| |
| − | This will give you information about satellites and how they are made and used.
| |
| − | Use of computers in science
| |
| − | Now all these technologies have changed the way we communicate. Many changes have happened and one important technology that has changed the way we work and learn is that of computers! You have already learnt about the history and development of computers. Now we will look at the various ways in which computers can be used for scientific research and study.
| |
| − | Making large calculations
| |
| − | Computers make it easy for scientists to do calculations with large numbers, for example number of cells or number of stars.
| |
| − | Make models for study
| |
| − | Experiments in science are of different kinds. Some are small, some are large, some are simple, some need lots of equipment, some are very complex and need lots of skill to do and some are impossible to do physically. Can you think of some examples of each of these kinds?
| |
| − | Computers help scientists in making models of complex and physically difficult experiments. If we want to find out whether a medicine will work or not, it is possible to build a computer model of the human cell for simulating how it will respond to the medicine. Similarly, we cannot go to a star and study the radio waves produced; but we can model it on a computer.
| |
| − | | |
| − | | |
| − | This is simulation of a supernova explosion. This has been made on the computer so that scientists can study what causes an explosion, what happens during an explosion and what is the effect afterwards.
| |
| − | This is a geological map of the world – you can see the rock structure in the Himalayas, Andes and other mountain ranges of the world. This map has been produced from many local, paper maps and putting them on the computer.
| |
| − | | |
| − | Connecting scientists and building databases
| |
| − | Science is everywhere. When computers are used to share the data collected, more people can have access to it. In Bengaluru, the National Centre of Biological Sciences wants to build a database of scientific data by getting data on trees and plants from all over Karnataka. Such a database will be available to many people.
| |
| − | What are computer simulations?
| |
| − | Earlier we used a software application called PhET with which you could study some phenomena on the computer. PhET is a simulation we can use to study science. Computer simulations are very useful for scientific research when a physical experiment may be very costly or dangerous or extremely time consuming to do. When a scientist is studying a problem, she will make assumptions about what causes the change and make predictions about what will change. This is based on past study of the subject and knowledge. This information can be input to the computer and the simulation will make all the calculations and show what changes happen. Sometimes, the changes that the simulation will show will be different from what the scientist predicted. This will help the scientists refine the theory.
| |
| − | The simulation shows the experiment on a computer. The scientist can change the inputs to see how the experiment changes. This helps in the development of new knowledge.
| |
| − | Simulations are different from animations
| |
| − | Computer models are different from animations. In an animation, we simply see a movie which shows a phenomenon happening. The inputs cannot be changed.
| |
| − | | |
| − | Lab exercises
| |
| − | Your teacher will show you the following. Write down what you observe in the two activities. Is there any difference between the two?
| |
| − | 1. Applications> Education> PhET> My Solar System
| |
| − | 2. Applications> Education> Kstars> Tools> Solar System
| |
| − | 3. Check out the following link on the solar system.
| |
| − | http://www.stumbleupon.com/su/569KDD/dd.dynamicdiagrams.com/wp-content/uploads/2011/01/orrery_2006.swf
| |
| − | | |
| − | | |
| − | | |
| − | | |
| − | Ecosystem
| |
| − | We have already seen what an ecosystem is. We will use the computer lab to access some resources on ecosystems. Before you do that, you need to have completed the following activities.
| |
| − | Pre-requisite activities
| |
| − | Please do the following activities and complete the questions.
| |
| − | 1. Go around the area near your school and record all that you see. This can include plants, animals and non-living things.
| |
| − | 2. What is the climate in your region like – seasons and rainfall?
| |
| − | 3. What crops, fruits and vegetables are there? Which animals, birds and trees are found? Are there any large animals (leopard, elephants) that come to your area?
| |
| − | Lab exercises
| |
| − | 1. We will watch a fun video on what are the various kinds of ecosystems (biomes) and the animals that live there. http://www.youtube.com/watch?v=90XU0B_ya6g&feature=related
| |
| − | 2. Watch the following videos
| |
| − | This is a short video about an ecosystem.
| |
| − | http://www.youtube.com/watch?v=WuejxJttBqo&feature=related
| |
| − | This is a video about the Chilka lake, Orissa ecosystem. This is an example of an aquatic ecosystem http://www.chilika.com/chilika_video_gallery.htm
| |
| − | Discuss the following questions with your teacher:
| |
| − | i. Are biome and ecosystem the same? What is the connection?
| |
| − | ii. Are all biomes found in all places? If yes, why? If no, why not?
| |
| − | iii. With a physical map, see how many biomes are found in India
| |
| − | iv. What is the name of ecosystem that your area is in? What region is it?
| |
| − | v. What important ideas did you get about ecosystems from this video?
| |
| − | 3. These are two videos that describe the food chain and food web
| |
| − | i. Food chain in Africa http://www.youtube.com/watch?v=3Bn7wdCP2v4&feature=related
| |
| − | ii. Interactions in an ecosystem http://www.youtube.com/watch?v=XJ6VtduDSyY&feature=related
| |
| − | iii. Description of a food chain and web http://www.youtube.com/watch?v=9eZBzfnAogU&feature=related
| |
| − | iv. Interactions and energy flow in an ecosystem http://www.youtube.com/watch?v=o_RBHfjZsUQ
| |
| − | Discuss the following questions:
| |
| − | i. When we say food web, what comes to your mind? Why do you think it is called food web?
| |
| − | ii. Can you think why there are few consumers and large number of producers? What happens when a consumer eats a producer?
| |
| − | i. Can you give examples of each of these categories in your area – producer, consumer and decomposer?
| |
| − | ii. For this web to work properly, what is needed?
| |
| − | iii. What is energy flow? How does it flow – from small organisms to large or large organisms to small? Why do you think so? What elements do you observe in the ecosystem that give you this idea?
| |
| − | iv. Is the tiger 'bad' because it ate the goats? Why is the tiger eating the goat?
| |
| − | 4. Read some of the following links on biogeochemical cycles.
| |
| − | http://www.geography4kids.com/files/cycles_intro.html
| |
| − | Heat, temperature and heat transfer mechanisms
| |
| − | You would have already been introduced to the concept of energy. We have seen that energy means ability to do work. When we say energy we usually think of movement, potential energy, kinetic energy, light, etc. What about heat?
| |
| − | Heat is a form of energy. When we rub our hands together, drag an object over another or even sharpen a tool, we will notice that heat is generated. Our hands will get warm and the tools will also become very hot. Why does this happen? Molecules inside an object are always moving and when their movement is increased, their energy is increased. And this is what is felt as heat. We can see that heat is a form of energy.
| |
| − | | |
| − | | |
| − | | |
| − | | |
| − | Activity
| |
| − | Let us think of a small activity. We will do it as a thought experiment! Do you know what a thought experiment is? It is something we conduct in our mind. Where we follow all the rules of science. Many scientists have conducted thought experiments to understand many difficult phenomena.
| |
| − | Let us say we have 4 bunsen burners. We will put three beakers – one of oil, water and milk on each of the burners and one metal spoon on the fourth burner. The quantity of oil, water and milk should be the same. We will keep the burner on for 4 minutes.
| |
| − | At the end of 4 minutes, we will measure the temperature of the oil, water and milk. Can you even touch the spoon at the end of 4 minutes?
| |
| − | What has happened to all these 4 substances? The temperature of all these 4 substances has increased. Why is this so? When we put something on a fire, it become hot. It becomes hot by absorbing the heat from the fire. How hot it becomes depends on the the material and the mass of the object. Every material absorbs heat differently. This depends on how the molecules are arranged in the object.
| |
| − | Lab exercises
| |
| − | Exercise 1: Now we will watch two videos
| |
| − | http://www.youtube.com/watch?v=S0TurHQp_AE – Heat as Energy
| |
| − | http://www.youtube.com/watch?v=wTi3Hn09OBs&feature=related – Temperature and Heat
| |
| − | Discuss the following questions with your teacher:
| |
| − | i. How does the water become more hot in the first video?
| |
| − | ii. How would you describe temperature?
| |
| − | iii. Why does the cup of water not heat the pool the same amount as the bucket of water?
| |
| − | iv. If I heat an iron rod as well as a pot of water on a wood stove for 10 minutes which would have the higher temperature, why? Ask your teacher about why this difference is there?
| |
| − | Exercise 2: How does heat get transferred?
| |
| − | We saw that heat is energy and this energy can be transferred from one body to another. We also saw that temperature is the way we measure the degree of hotness of an object.
| |
| − | But how does this heat get transferred? When we heated milk, oil and water as well as the spoon, we saw that the temperature of each of them was different. We also saw that the temperature depended on the molecular structure.
| |
| − | The molecular structure of the substances also determines how the heat is transferred through the substance. Watch the following two videos to see how heat is transferred in solids and liquids.
| |
| − | http://www.youtube.com/watch?v=77R4arwD8G8&feature=related – Heat transfer by conduction
| |
| − | http://www.youtube.com/watch?v=ON2Y3FEk_UI&feature=related – Heat transfer by convection
| |
| − | Discuss the following questions with your teacher
| |
| − | i. Can you lift a hot vessel from a stove with your hands? What should you do? And why does it work? (Do not try this before understanding the science behind!!)
| |
| − | ii. Convection currents work in fluids – liquids and gases, which means they work on air. Can you think of the effect this will have on weather?
| |
| − | iii. Is there any connection between the conduction we talk about in heat and electrical conduction?
| |
| − | iv. What substances are generally good conductors of heat? And electricity? And why?
| |
| − | Chapter summary
| |
| − | 1. Science and technology are linked; technology has helped the development of science.
| |
| − | 2. ICTs have changed the way we work. Some major inventions are radio, telephone and the cell phones. Along with satellites, these have changed the way we look at the world and information available.
| |
| − | 3. We have seen that the cell phone functions like a computer and camera also! This is possible because of the integrated circuit that instructs the phone what to do.
| |
| − | 4. Computers have made many improvements in how we study science. They can be used to simulate models, do large calculations,develop databases and help connect people.
| |
| − | 5. The computer and Internet technologies can also be used for studying science in schools.
| |
| − | 6. You have studied about ecosystems, biomes, food webs and biogeochemical cycles through videos.
| |
| − | 7. You have seen the difference between simulation and animation.
| |
| − | Exercises
| |
| − | 1. Take a radio and tune to a particular station and listen. Write down all that you hear. Ask your teacher to explain the 'disturbance' that you hear when you move from one station to another. What does this announcement mean? 'You are listening to AIR.'
| |
| − | 2. Find out who are the major cell phone providers in your areas. What does it cost to make a cell phone call.
| |
| − | 3. Open the PhET simulation on Colour Vision. Run both the simulations – RGB Bulbs and Single Bulb. Then, answer the following questions:
| |
| − | i. When only one bulb is used, what colour does the man see? Why?
| |
| − | ii. When more than one colour is used, what colour does the man see? Why? Does this change if I move the sliders on each of the bulbs the man sees? If it changes, why does it change?
| |
| − | iii. When all the three bulbs are used, what is the colour that the man sees? Where else do we see white light? If R,G,B when mixed give the white light, what can you say about the nature of the red, green and blue.
| |
| − | iv. When does the man see any colour and when does he see black?
| |
| − | v. What is the filter doing? Explain the difference in colour between the source being monochromatic (single colour) and white.
| |
| − | 4. Open the PhET simulation on Friction under Physics/ Motion. Run the simulation and answer the following questions.
| |
| − | i. What do the moving green and yellow circles indicate?
| |
| − | ii. When you are rubbing the yellow book on the green book what happens? How do you know that the heat is being generated?
| |
| − | iii. When the temperature goes very high, the yellow circles fly off. What does this mean physically?
| |
| − | Additional resources
| |
| − | 1. http://www.nrao.edu/ - For a description of radio astronomy
| |
| − | 2. http://www.computersciencelab.com/ComputerHistory/History.htm – Growth in computer technology
| |
