6 Gen Science EM 2024-25 Past Paper PDF

11 Water in Our Life During the festival of Holi, Arvind was playing A with his friends. They had gone to the market and AN bought differ...

11 Water in Our Life During the festival of Holi, Arvind was playing A with his friends. They had gone to the market and AN bought different colours. They mixed each colour in a bucket of water and poured mugs full of water on each other. They G sprayed colours on each other as well. Arvind and AN all his friends were completely drenched and enjoyed themselves a lot. Then they decided to go and have a wash. L They went to a well and TE took bath with several buckets of water. They washed their clothes as Fig. 1 well. Activity-1: Water and its uses T, If there was no water, what would happen to Arvind and his friends? Make a group of five students and For what purposes do we need ER water in our daily life? discuss the uses of water in their daily Do plants and animals also require life. Write down the uses. water like us? Classify the above uses of water in three SC 11.1. Water in Our Life groups. We need water to perform several day to day activities like cooking food, 1. Uses in a house or family. washing clothes, cleaning utensils etc. We 2. For agricultural purposes. can't survive without water for even a single day. 3. Others. World wide over 1 billion people use less than 6 litres of water per day. Water in Our Life 101 Government’s Gift for Students' Progress  A AN G L AN TE T, ER Fig. 2 : Uses of water in our daily life 11.2. Measuring the volume of water How do we measure the volume SC of water? Aravind used buckets of water to clean the colours from his body and his clothes. We can store water in different types of He said he used seven buckets of water. vessels. Often, we say, a glass of water, Is bucket a measure of the volume of bucketful of water, bottle of water etc. water used? Do you know any specific unit of measurement of volume? Almost 4 million people die each year world wide from water related diseases. Water in Our Life 102 Government’s Gift for Students' Progress Activity-2: Quantity of water Find out from your parents and grandparents whether they also paid for Collect different used water bottles or water. water pouches from nearby shops. Observe their labels. What quantity of Activity-3: How much water do we water is mentioned on the label? Record use daily? your observations in your notebook. We use water for different purposes. Can A you estimate how much water your family Do all the bottles and pouches uses in a day? Can you guess? AN have the same quantity of water? Record your estimates in table 1. Also You can also ask the water-vendor think how you could reduce the amount how much water there is in a water of water used and write how much G can or bottle. water you can save. Do you know? AN Table 1 Work Water How much water Volume of water and other liquids is used can you save? measured in litres and millilitres. The (In liters) (In liters) L water tanks in some villages and most TE towns and cities have the capacity to Drinking store gallons of water. Gallon is also a Toilets measure of volume of liquids. Bathing T, Water level in the reserviors is measured Washing in feet. Water released from dams and clothes ER projects during floods is measured in Other works cusecs (cubic centimeters/sec). Total Think: SC To estimate in litres the amount of Air and water are freely available in nature water used, take any 1 litre bottle and but now people have to pay for water along find out how many bottles of water with other commodities. are needed to fill a bucket, a glass, a mug etc. Now, find out how much water is used in a whole day by you. 43% of water related deaths are due to diarrhoea. Water in Our Life 103 Government’s Gift for Students' Progress and your family. (Also, calculate the List out the sources from where amount of water you and your family were you get water in your village/ able to save.) town. You have a rough idea of how much Are the sources from where water your family uses in a day. With this you get water for your daily information you may be able to calculate needs and crops the same or the approximate quantity of water not? Give your reasons. A required for your colony/ village/ town/ Do you know? city. For this, you will need to know the Water is not only available from AN population as well. Ask your teacher about sources such as the rivers, lakes and population. ponds but also present in certain fruits Approximate quantity of water and vegetables. Fruits like watermelon used per day by a person and vegetables like cucumber contain G........................... in litres. a lot of water. Can you suggest some other examples? Our body also Number of people in the colony / village / town........................... AN contains 70% of water by weight. Think, why we take juicy fruits in Approximate quantity of water summer. used per day in the colony / village / 11.4. Water on the earth L town................................ in litres. There are different sources of water TE on the earth. We know that nearly Approximate quantity of water 3/4th of the surface of the earth is used per month in the colony / occupied by water. Is this water useful village / town................................ in for us? litres. T, Can we drink the water available in the Approximate quantity of water per sea? year in the colony / village / town Sea-water is salty. Hence it is not used ER................................ in litres. in our daily needs but water used by us Imagine how much water is needed across in our daily purposes is not salty. It is the total world population per day / month / known as fresh water. Water in ponds, puddles, river, from tube-wells and our SC a year. taps at home is usually fresh water. 11.3. Where do we get water from? Activity-4: Safe drinking water We get water from different water stages sources in our surroundings. In most Meet your panchayat officer and villages wells, canals, tanks, ponds, rivers, collect infor mation about safe etc are the main water sources. drinking water scheme in your village. 98% of water related deaths occur in the developing world. Water in Our Life 104 Government’s Gift for Students' Progress Don't forget to prepare questionnaire How was the well dug? for interview. Display your observations Have you seen a borewell being in your wall magazine. dug? Write the process in your 11.5. Stages of safe drinking water notebook. supply Tank / Pond Do you know? Even though the river Krishna flows A Filtration through Nalgonda district, it suffers from severe water scarcity. They are AN Aeration suffering from flourosis. This is because ground water is Chlorination contaminated with flourine. G Tapping of ground water by digging a Over head tank ANwell or borewell is a tough job. Many people put in a lot of hard work in this process. We need to appreciate this and Taps preserve water. Observe the stages in the supply of L protected drinking water as shown in You have read about the different TE the flow chart. Based on your types of water sources in our observation, write the steps followed in surroundings. The water level in them supplying the water to households from depends upon rainfall. Generally, we water resources. Compare these steps observe that the water levels in wells T, to the method of water supply in your or other water sources go up in rainy village. Discuss your observations. season and down during the summer season. ER 11.6. How the well was dug? Activity-5: Go to nearby village and look What happens if there is less rain fall at a well from where people get drinking or too much rain fall? water. Can you estimate the approximate 11.7. Droughts - water scarcity SC volume of water in the well? Collect information from elders in the village Activity-6: Form groups of 4 to 5 about the level of water in the well over students and discuss the following the years. topics Is the water level constant or has it changed? Unsafe water is the biggest killer of children under five; around 90% of all diar- rhoeal deaths are in this age group. Water in Our Life 105 Government’s Gift for Students' Progress in each group. Prepare and submit a Activity-7: Droughts have a severe group report. The topics to be discussed impact on our lives. are: Here is a Ramana's letter for you try to Topic-1 : What will happen if rainfall is understand how drought affects our less this year than the last year? lives. Topic-2 : What would happen if there is no proper rainfall for five years? Kosgi A Topic-3 : What could be the possible reasons for water scarcity in a particular Dear Firoz, AN place? I hope you are fine there. Nowadays, we Topic-4 : What problems can arise due are facing severe problems due to to water scarcity in a particular place? G drought. For the last five years we have AN had no rains. All our fields have dried and there are cracks on them. We fail to grow any crop. My father invested money on bore wells with no results. Now we get L water, after a great struggle from the TE bore-well which is five - six kilometers from our village. The days have become Fig. 3 In our region, if there is no rain for very bad. Several people have sold their T, a long period (4 to 5 years), it may cattle and migrated to Hyderabad and cause droughts. During this period, Bengaluru. My family also wants to do it is very difficult to get food and ER fodder; drinking water is scarce. so. I request you to ask your parents to People need to travel long distances search for a job for my father at your to collect water. Soil becomes dry as a result agriculture and cultivation is place. My father may have been a well- SC difficult. Many people who depend known, rich farmer here but he is willing on far ming for their livelihood, to do any kind of job there. migrate to other places in search of jobs. In our state, Mahabubnagar Yours loving friend districts are treated as drought prone areas. Ramana The recommended daily water requirement for sanitation, bathing, cooking and consumption is approximately 50 litres per person per day. Water in Our Life 106 Government’s Gift for Students' Progress  What problems were faced by List out those situations in our life where Ramana? Why did problems we waste water unwisely and make come? suggestions to avoid this. How can Firoz help Ramana? 11.8. Floods a natural hazard Water scarcity is a problem in some districts of our state, as mentioned Activity-9: Waterless conditions lead to droughts while high water levels due to A earlier. Here rainfall is less and farmers are largely dependent on irrigation using more rain fall can leads to floods. AN underground water to raise crops. Usually, during the rainy season, you may What will happen if farmer grow have come across pictures of this type in crops that require more water in newspapers (Fig. 4). Discuss the following. G these districts? If several bore wells are dug and AN underground water is tapped constantly, what will happen to the source of ground water? L Discuss with your friends and teachers TE about the reasons that can cause reduction of ground water. Fig. 4 Activity-8: How much water do we What does the picture tell us? waste? Does excessive rainfall in certain areas T, After playing in the ground you may of our country lead to such a condition? wash your hands and legs under the tap ER in your school. Measure the time the tap Are there other reasons as well that is on open for you to complete your can lead to this situation? wash. Then take a bucket put it under Did you ever face or hear about flood? SC the tap open the tap for the same time that you measured with the same flow On the basis of the newspaper cutting of water. How many students of your or your own experience in this matter class can wash thier hands and feet with if any, write down a few lines on floods. the bucket of water that you collect from We can't live single day without the tap? water. It is unwise pumping of water Inability of harvesting rainwater is one of the reasons for drought. Water in Our Life 107 Government’s Gift for Students' Progress that leads to drought. Arvind decided 3. Why do people need protected that water is precious. Don't waste even drinking water scheme? a single drop of water. We must 4. List out the activities that we preserve water not only for us but also perfor m in our daily life that for future generations. consume water. Keywords 5. In --------- season we face severe A Water sources, drought, floods, water scarcity. Give your reason. migration 6. The taste of sea water is ------- AN What we have learnt? a) Salty b) Tasteless c) Bitter d) Sweet We need water for domestic use, 7. If we use water unwisely what will G agriculture, industries. happen in future. Write your We get water from sources like wells,AN suggestions to prevent water wastage. ponds, lakes, rivers etc. 8. Prepare a map of your village Of the water available on the earth, showing different water sources. only 1% is fresh water. 9. Make a pamphlet on "Don't waste L We depend on rains for water. water". Display it on wall magazine. TE Long periods of less rainfall usually 10. Collect information about water causes condition of droughts. related games and make a scrap book. Floods are natural disasters they cause 11. Find out the relationship between T, property damage and loss of life. water shortage and drought? 12. Justify the statement "droughts and Improve your learning ER floods are a result of actions made 1. How can you say by man". What are your reasons. water is necessary 13. Aravind never forget to switch off for us? SC water pumping motor in time. Do 2. Pavan wants to you support him? Why? know the 14. If people are suffering due to severe measuring units of water. What will floods, what would you do to help you tell him? them? ***** It takes up to 5000 litres of water to produce 1kg of rice. Water in Our Life 108 Government’s Gift for Students' Progress  12 Simple Electric Circuits Niharika's father Ranganna had to go to the fields after dinner. A Watering the field in the night had become a usual practice due AN to power cuts throughout the day. Ranganna walked out of the house and called Niharika asking for a torch-light. She took the G torch and cells out from the cupboard and handed over the torch-light to her father after AN inserting the cells. He switched on the torch but it did not light up. Why it did not light up? What could be the L problem? TE Was there something wrong with the Fig. 1 torch-light? Niharika took back the torch and opened it and realised her mistake. She had inserted the cells in a wrong way. She changed the position of the T, cells and handed over the working torch-light to her father. ER 12.1. Cell Fig. 2 Why does the position of cells affect the working of a torch-light? What does a cell contain? How does it The cell consists of a cylindrical metal SC help the torch light glow? Now let us can. Its heaviness suggests that it is filled take a cell and observe it carefully. with some chemicals. The protrusion on Activity-1: Observe the cell one end is due to a carbon rod in the Let us take a torch cell (Fig. 2) and observe it. Can you describe it? Write centre. At the top of the cell a metal your observations in your notebook. cap is fixed. The entire can is sealed. Greek philosopher Thales of Miletus (c.624–546 BCE) discovered static electricity. Simple Electric Circuits 109 Government’s Gift for Students' Progress Have you seen (+) and (-) signs on a cell? Why do bulbs and cells have two These signs indicate the two terminals of terminals? a cell. How does a bulb glow with the Note: help of a cell? Do not connect the two terminals of a cell with a single wire. 12.3.Simple electric circuits 12.2. Bulb : Activity-2: Take four wires of different A colours, say blue, green, red and yellow, each about 15 cm long. Electric wires AN Glass chamber Filament are often covered with plastic. First, remove about two centimeters of the Terminals plastic covering from both ends of each G Metal Cap wire. Now attach two wires (Blue and Terminals AN Green) to a bulb and two wires (Red and Fig. 3 Yellow) to a cell with a cello tape or cell holder as shown in Fig. 4(a). We can use Observe a torch-bulb or an electric a cell holder to hold the cells and wires bulb carefully (Fig. 3). together tightly. L A torch bulb consists of a glass chamber fixed on a metal cap (metal [Take an old tube of a bicycle and cut it TE base). Observe the two metal wires. How are they fixed? One wire is into narrow bands. Each band should be attached to the metal cap and the other wide enough to hold the two terminals of is attached to the base at the centre of the metal cap. These wires act as two the cell firmly. This is your cell holder.] terminals. The two terminals do not T, Now connect the wires in different forms touch each other. as shown in Fig. 4(b) to 4(g). In each case, Electric bulbs have two protruded parts ER on the back side of the metal cap. check whether the bulb glows or not. Observe them. Break the glass chamber Record your observations in table1. and check how the wires are arranged inside. (Take care not to pierce the SC pieces of glass). Identify the difference between torch bulb and electric bulb. The part of the bulb that glows is the filament, which is a thin spring like wire attached to the two metal wires inside the glass bulb. Fig. 4 (a) English scientist William Gilbert (1544–1603) was the first person to use the word “electricity.” He believed electricity was caused by a moving fluid called humor. Simple Electric Circuits 110 Government’s Gift for Students' Progress  In which case does the bulb glow? Why? In which case the bulb does not glow? why? The blub glows only in connections shown in Fig.4(d) and Fig.4(e). In Fig.4(d) and Fig.4(e), there is a closed path for the flow Fig. 4(b) Fig. 4(c) of electric current. In Fig.4(f), Fig.4(g), Fig.4(b) and Fig.4(c), there is no closed path A for the flow of electric current. In Fig.4(b), Fig.4(c) the bulb is connected to the same AN terminal of the cell. G Fig. 4(d) Fig. 4(e) AN Fig. 5 : A simple electric circuit L 12.3.1. What is a circuit? TE Fig. 5 shows a simple electric circuit. It Fig. 4(f) Fig. 4(g) consists of a cell (power source), a bulb, and connecting wires. In an electric circuit, the Fig. 4(b) to 4(g) electric current flows from positive terminal T, to negative terminal. Table 1 An electric circuit provides a complete path ER Connection Does the bulb glow for electricity to flow between cell and the (Yes/No) bulb. The top part of the cell with protrusion Fig 4(b) is positive terminal and bottom part is negative trminal. SC Fig 4(c) A similar circuit exists for an electric bulb Fig 4(d) which we use in our houses. The two electric Fig 4(e) supply wires are connected to the two Fig 4(f) terminals of the bulb through a switch. When the switch is ON the circuit provides Fig 4(g) complete path for electricity. American printer, journalist, scientist, and statesman Benjamin Franklin (1706–1790) carried out further experiments and named the two kinds of electric charge “positive” and “negative.” Simple Electric Circuits 111 Government’s Gift for Students' Progress  Can you observe a bulb and say if it can glow or not when connected in a circuit? B Do you find any difference in the A filament of glowing bulb and the bulb that is not glowing ? A Take one spoilt bulb and connect it in a AN Fig. 6 : Circuit with a switch circuit. It doesn’t glow. When the filament of the bulb is broken, then no other end is left free. Does the bulb electric current will pass through it as glow? G the circuit is not closed. Hence the bulb Now touch the safety-pin to pin A and doesn’t glow.. AN observe the bulb again. What happens? 12.4. Switch : Why doesn't the bulb glow when the We use switches to put ON or put OFF safety pin is left free at one end? L the torch light. Similarly we use various In the above activity, the safety pin is TE switches in our house to put ON or put used to close /open the circuit. Electric OFF the electric bulbs, tubes, fans etc. switch is an arrangement to close or What is a switch? How does it work? open (break) a circuit. T, Let us observe The switch allows the flow of electricity Activity-3: Electric Switch when it is ON and cuts off the flow of ER electricity when it is OFF. In this way, Connect a circuit on a wooden plank the switch is used to allow / stop the or on a thermocol sheet as shown in flow of electricity to the bulb or any other SC Fig. 6. electrical device. Insert two drawing pins at A and B. Insert a safety pin in between A and B, The flow of electricity in a circuit is called such that one end of the pin is current. completely in contact with B and the Italian biologist Luigi Galvani (1737–1798) touched two pieces of metal to a dead frog’s leg and made it jump. This led him to believe electricity is made inside animals’ bodies. Simple Electric Circuits 112 Government’s Gift for Students' Progress 12.5. Torch-light : Draw pictures showing different positions What does a torch consist of? of cells and glowing of bulb. Can you find out why the bulb glows only when cells What makes the torch bulb glow? are placed in a particular position? Take a torch and observe its internal parts 12.6. Electric Conductors and (Fig. 7). insulators In activity-2, we used wires after Glass Copper wire removing the plastic covering at both A Switch Metal Spring Cells Reflector the ends. Why don't we use the wires without removing the plastic covering? AN What material do you find in electric wires? Why are we advised to wear rubber chappals while working with electricity? G Hollow Cyllindrical Barrel Bulb ANLet us find out. Fig. 7 : Inside view of a torch-light Activity-5: Identifying conductors Torch-light is used as a source of light. and insulators The parts of a torch-light are hollow Take the circuit which we used in cylindrical barrel, cells, bulb, switch, glass activity-3. As shown in Fig. 8, Remove L cover and metal spring. the safety-pin from the drawing pins TE Torch consists a hollow cylindrical barrel so that you have two open terminals A in which cells are fitted. At one end of and B. Insert different objects like a hair it there is a lid with screw which can be pin, safety pin, eraser, plastic scale, opened and closed. When the lid is closed match stick, piece of a metal bangle, T, and switch is ON, the circuit is piece of a glass bangle, paper clip etc. completed and current flows in the in the gap between A and B. With each circuit which makes the bulb glow. insertion, check whether the bulb glows ER In Niharika's case, it was just the position or not. Record your observations in of cells that made the bulb to glow. Can table 2 for each case. you predict other reasons for the torch not working ? SC Activity-4: Let us do Take a torch which has two cells. Arrange B the cells in the torch in as many ways as A you can. In which cases does the bulb glow and in which cases it doesn't? Fig. 8 : An open electric circuit Danish physicist Hans Christian Oersted (1777–1851) put a compass near an electric cable and discovered that electricity can make magnetism. Simple Electric Circuits 113 Government’s Gift for Students' Progress  Table 2 S.No. Object Name of the Does the bulb glow Material (Yes/No) 1. Hair pin Metal Yes 2. Eraser Rubber A 3. Plastic scale Plastic AN 4. Match stick 5. Divider from G geometry box 6. Piece of paper AN 7. Iron nail L 8. Piece of Glass bangle TE 9. Pencil lead 10. Paper clip T, 11. Piece of chalk ER 12. Safety pin If you look at table 2, after recording Substances which allow electric SC your observations you will find that the current to flow through them are known as conductors of electricity. bulb glows in some cases and does not Substances which do not allow electric glow in other cases. Can you guess the current to flow through them are known reason? as insulators. Michael Faraday (1791–1867), an English chemist and physicist, developed the first, primitive electric motor. Simple Electric Circuits 114 Government’s Gift for Students' Progress Using the above definitions, can you From childhood, Edison was of an group the objects you obser ved in inquisitive nature and he learned science Table-2 as conductors and insulators? by performing experiments himself. You Make a list of objects and group them will be amazed to know that in his lifetime he invented more than one thousand as conductors and insulators and write inventions. in table-3. Table 3 Even an intelligent scientist like Edison had A Conductors Insulators to work hard for many years before he could AN make a bulb that worked. First of all, he passed electricity through a thin, thread-like platinum wire. G He noticed that the wire Edison’s ANdid give out light after first bulb being heated, but it burned out after only a few seconds. 12.7. The story of bulb : Edison then thought that if the air surrounding the wire coil was removed L The story of invention of bulb is very then, perhaps, the wire would not burn interesting. We may think that a bulb is TE out so quickly. a very simple gadget, just press a switch and it lights up. But do you know that He made a glass casing and fitted a filament of platinum wire in it. He then many scientists worked hard for many removed all the air from within the glass years before the first successful bulb was T, casing. He passed an electric current made? One of them was Thomas Alva through the wire and, to his delight, the Edison who ultimately succeeded in bulb lit up and continued to glow for ER making the first bulb. eight long minutes. With this achievement he felt happy and began experimenting with different materials while searching for a better choice of SC filament. He tried cotton thread coated with soot. This filament burned continuously for 45 hours. One summer day he saw a man fanning himself with a bamboo fan. An idea Fig. 9 : Thomas Alva Edison striked his curious mind - Building on his earlier discoveries, Michael Faraday (1791-1867) invented the electric generator. Simple Electric Circuits 115 Government’s Gift for Students' Progress