202110187-APEX-STUDENT-WORKBOOK-SCIENCE-G07-PART1

SESSION 1 7. ELECTRICITY 1.1 Mind Map INTRODUCTION TO CELL AND DRY CELL 1.2 Terminology i. Dry cell – A standard dry cell comprises a zinc anode, usually in the form of a cylin- drical pot, with a carbon cathode in the form of a central rod. ii. Chemical energy –Chemical energy is the potential of a chemical substance to un- dergo a transformation through a chemical reaction to transform other chemical substances. iii. Electrical energy – Electrical energy is defined as an electric charge that lets work be accomplished. iv. Batteries – A battery is an electrochemical cell (or enclosed and protected material) that can be charged electrically to provide a static potential for power or released electrical charge when needed. 1.3 Key Concepts i. Dry cell is an electrical device which converts chemical energy into electrical energy. ii. An electrical cell consists of two terminals namely positive (+ve) and negative (–ve) terminals. SESSION 1. INTRODUCTION TO CELL AND DRY CELL 99

iii. A dry cell consists of a container made up of zinc metal which serves as a negative terminal and a carbon rod with a metal cap serves as a positive terminal. iv. In a closed electric circuit, the passage of electric current is from one terminal of the electric cell to the other terminal. 1.4 Conceptual Understanding Q1. Choose the correct answer: [Refer to TB page 72 Q8](iii)) Which one of the following is used as a light source? a) Cassette player b) Electric mixer c) Rice cooker d) Table lamp A. (d) Table lamp SESSION 1. INTRODUCTION TO CELL AND DRY CELL 100

SESSION 2 ELECTRIC SYMBOLS AND CIRCUIT DIAGRAM 2.1 Mind Map 2.2 Terminology i. Open circuit –Open circuit is a broken path for an electrical current due to an open switch or An electrical circuit in which the continuity is broken so that current does not flow. ii. Closed circuit – An electric circuit providing an uninterrupted, endless path for the flow of current. iii. Switch –A device for making and breaking the connection in an electric circuit. iv. Circuit Diagram –Circuit diagram is a graphical representation of an electrical circuit. 2.3 Key Concepts i. A graphical or schematic representation of an electric circuit is known as circuit dia- gram. SESSION 2. ELECTRIC SYMBOLS AND CIRCUIT DIAGRAM 101

ii. Symbols for each component in a circuit are used to draw a circuit diagram. iii. In a circuit, there should be a source of electric current, which is a cell or battery. iv. When the switch is on, the circuit is complete from the positive terminal of the battery to the negative terminal. It is known as a closed circuit. v. When the switch is off, the circuit is open and no current flows. vi. A switch therefore controls the flow of current in the circuit. 2.4 Conceptual Understanding Q1. Fill in the blanks: [Refer to TB page 71 Q6](a), (b), (c), (e)] terminal. a) Longer line in the symbol for a cell represents its b) Smaller line in the symbol for cell represents its terminal. c) The combination of two or more cells is called a . e) The device used to close or open an electric circuit is a . A. a) Longer line in the symbol for a cell represents its positive terminal. b) Smaller line in the symbol for cell represents its negative terminal. c) The combination of two or more cells is called a battery. e) The device used to close or open an electric circuit is a switch. Q2. Mark ‘T’ for the statement which is true and ‘F’ if it is false. Give reasons for choice of answer: [Refer to TB page 71 Q7] (c) To make a battery of two cells, the negative terminal of one cell is connected to the negative terminal of another cell. (e) The switch is used to close or open an electric circuit. A. (c) False. To make a battery of two cells, the negative terminal of one cell should be connected to positive terminal of another cell. SESSION 2. ELECTRIC SYMBOLS AND CIRCUIT DIAGRAM 102

(e) True. The switch is a device connected in an electric circuit. If the switch is in “ON” position the circuit is closed and current flows through the circuit. If the switch is “OFF” the circuit is open and current does not flow through the circuit. Q3. Choose the correct answer: [Refer to TB page 72 Q8(ii)] (ii) Device used to close or open an electric circuit is: (A) Electric bulb (B) Battery (C) Switch (D) Fuse A. [C] Switch 2.5 Communication Through Drawing and Model Making Q1. Draw the symbols of the following electrical components. [Refer to TB page 71 Q1] a) cell b) battery c) switch d) electric bulb A. SESSION 2. ELECTRIC SYMBOLS AND CIRCUIT DIAGRAM 103

Q2. Draw an electric circuit diagram consisting of a cell, a bulb and an electric switch. [Refer to TB page 71 Q2] SESSION 2. ELECTRIC SYMBOLS AND CIRCUIT DIAGRAM 104

A. Q3. Draw the symbols for the electrical components in a table. (Pg:72, TB Ques:10) A. SESSION 2. ELECTRIC SYMBOLS AND CIRCUIT DIAGRAM 105

Q4. Draw the circuit diagram for the following series connection.(Pg:72, TB Ques:11) A. SESSION 2. ELECTRIC SYMBOLS AND CIRCUIT DIAGRAM 106

SESSION 3 SERIES AND PARALLEL CIRCUITS 3.1 Mind Map 3.2 Terminology i. Series circuit – A series circuit is a closed circuit in which the current follows one path. ii. Parallel circuit – A parallel circuit is a closed circuit in which the current divides into two or more paths before recombining to complete the circuit. 3.3 Key Concepts i. An electric circuit is classified into two types based on the path of flow of current. These are series circuit and parallel circuits. SESSION 3. SERIES AND PARALLEL CIRCUITS 107

ii. In a series circuit, electricity has only one path to flow through. All the electrical components are connected in this path. If any one of them malfunctions, the circuit will be incomplete. When bulbs are connected in series, if one stops glowing, none of them glow. iii. A parallel circuit has more than one path for the flow of electricity. Each component is connected in a separate path. When bulbs are connected in parallel, even though one stops glowing, the others glow. iv. In our households, components are connected in parallel. 3.4 Conceptual Understanding Q1. In a series connection of bulbs if one bulb fails, why do all the other bulbs go off? [Refer to TB page 71 Q3] A. In series connection of bulbs, the flow of current follows a single path. So, if one bulb fails, the circuit is broken at that point. As the current does not flow any further, the other bulbs also go off. Q2. Write the differences between a series connection and parallel connection. [Refer to TB page 71 Q4] A. Differences between a series connection and parallel connection: Series connection PPaarraallelellccoonnnneeccttioionn In a series circuit, electricity A parallel circuit has more has only one path to flow than one path for the flow of through. electricity. When bulbs are connected When bulbs are connected in series, when one stops in parallel, even though one glowing, none of them glow. stops glowing, the others glow. SESSION 3. SERIES AND PARALLEL CIRCUITS 108

In series connection, the In parallel connection, all –ve terminal of a cell is the +ve terminals are joined joined to +ve terminal of the together by a single second cell and the –ve of conductor and all -ve the second cell is connected terminals to +ve terminal third cell and are joined together by so on. another single conductor. In series combination, the In parallel combination, the brightness of a bulb brightness of bulb remains increases. steady. There will be a steady flow of electric charge. Q3. Mark ‘T’ for the statement which is true and ‘F’ if it is false. Give reasons for choice of answer. [Refer to TB page 71 Q7](a), (b)) a) In series circuit the electricity has only one path. b) In parallel circuit the electricity has more than one path. A. (a) True. As the ‘–ve’ is joined to the ‘+ve’ of the second cell and so on, there will be only a single path for the flow of electricity. (b) True. As all the positive ends are joined to one terminal and all the negative ends joined to another end; there are many paths for the flow of electrical charges. SESSION 3. SERIES AND PARALLEL CIRCUITS 109

SESSION 4 HEATING EFFECTS OF ELECTRIC CURRENT 4.1 Mind Map 4.2 Terminology i. Fuse –A safety device consisting of a strip of wire that melts and breaks an electric circuit if the current exceeds a safe level. ii. Compact Fluorescent Lamps – Compact Fluorescent Lamps(CFLs) are energy–saving light bulbs, which last longer and use far less energy than traditional (or incandescent) light bulb for the same level of light intensity. iii. Miniature Circuit Breaker –Miniature circuit breaker; a small trip switch operated by an over- load and used to protect an electric circuit, especially a domestic circuit as an alternative to a fuse. iv. Watt –The SI unit of power. v. Kilo watt –A measure of one thousand watts of electrical power. vi. Heating effects of current – The heat produced when an electric current passes through a material, due to resistance. vii. Filament –A conducting wire or thread with a high melting point, forming part of an electric bulb or thermionic valve and heated or made incandescent by an electric current. SESSION 4. HEATING EFFECTS OF ELECTRIC CURRENT 110

4.3 Solved Examples Q1. The meter reading in Ayub’s house in January is 400 units, February 580 units. Calculate how much his parents would have to pay towards electricity bill of February? The unit cost is Rs. 3.05. A. Meter reading in January = 400 Meter reading in February = 580 No. of units used in February = 580 –400 = 180 At the rate of Rs. 3.05 per unit, the amount of electricity bill = 180 x 3.05 = Rs. 549 Note: Unit cost differs in different areas and also on the slabs. Electricity provided for domestic purposes is cheaper than compared to that for commercial or industrial purposes. Q2. Suppose in a house there are four bulbs of 100 W each, six of 60 W each and six of 40 W each. All of them are used for two hours a day. How many units of electricity will be used up in 30 days? How much will they have to pay at Rs. 2.80 /–per unit? A. Total power used = (4 x 100 W) + (6 x 60 W) + (6 x 40 W) = 1000 W = 1 kW Total power used every day = 2 h x 1 kW = 2 kWh In 30 days, power used = 2 x 30 kWh = 60 kWh The cost of the power is = Rs. 2.80 x 60 = Rs. 168/– 4.4 Key Concepts i. It is noticed that when an electric current passes through a wire, the wire gets heated. ii. The material, length, and thickness of wires directly influence the amount of heat produced in a wire. iii. This is the reason why different types of wires are used in different appliances as per the requirement. SESSION 4. HEATING EFFECTS OF ELECTRIC CURRENT 111

iv. When the filament of a bulb gets heated to a high temperature it starts glowing and gives out light. v. Devices can get overheated and catch fire. To avoid this, fuse is connected in series to the circuit. vi. A fuse is made up of a special alloy that gets heated quickly and melts, if the current is too high thus breaking the circuit. vii. MCBs or miniature circuit breakers (MCB) have replaced fuses now a days. The advantage they have over a fuse is that, it has a switch which goes off automatically if there is overheating. They can be reset, whereas fuses need to be replaced. viii. Now a days fluorescent tube lights are used in place of filament bulbs to reduce the wastage of light. ix. The electrical power consumed for household purposes, for agricultural purposes and for industrial use is measured in kilo watt hours. x. One kilo watt = 1000 watts. xi. Watt is the unit of power. 4.5 Conceptual Understanding Q1. What is the advantage of a miniature circuit breaker? [Refer to TB page 71 Q5] A. i. Miniature circuit breakers (MCB) are being used extensively in place of fuses. ii. They have switches which automatically turn ‘off’ when current in a circuit exceeds the safe limit. iii. This breaks the circuit. If we turn the switch ‘on’,the circuit is once again complete. iv. They can be easily reset, whereas fuses need to be replaced. Q2. Mark ‘T’ for the statement which is true and ‘F’ if it is false. Give reasons for choice of answer. [Refer to TB page 72 Q7](d)) (d) When the electric current through the fuse exceeds a certain limit, the fuse wire melts and breaks. A. (d) True. The fuse wire is made up of an alloy which has a low melting point. If the electric current through the fuse exceeds a certain limit, the heat produced by electricity causes the fuse wire to melt and break. SESSION 4. HEATING EFFECTS OF ELECTRIC CURRENT 112

Q3. Choose the correct answer: [Refer to TB page 72 Q8](i), (ii)) (i) Arun buys four bulbs of 15 W, 40 W, 60 W and 100 W respectively. Which one should be used in his room as a night blub? (A) 15 W (B) 40 W (C) 60 W (D) 100 W (iv) Safety device used in electric circuit is: (A) Electric bulb (B) Battery (C) Switch (D) Fuse A. (i) [A] (iv) [D] Q4. Match the following: [Refer to TB page 72 Q12] A. Q5. Fill in the blanks: [Refer to TB page 71 Q6](d)) . (d) Safety device used in an electric circuit is SESSION 4. HEATING EFFECTS OF ELECTRIC CURRENT 113

A. (d) Safety device used in an electric circuit is fuse. 4.6 Information Skills and Projects Q1. Visit your classmates’ houses. Find out the meter readings of three months. Record your observations. Ask your parents about how electricity bill is paid. [Refer to TB page 72 Q9] A. Students’ Activity. Electricity bills are paid in the electricity department bill paying centre or we can also pay at e–seva, mee–seva centers or we also have the facility to pay bill online. —— CCE Based Practice Questions —— AS1-Conceptual Understanding Very Short Answer Type Questions 1. Fill in the blanks. [Refer to Session 7.4 ] is used as a source for light. (i) (ii) 1 KW = . (iii) When electric current passing through a is high, it heats up and melts, breaking the circuit. (iv) Most of the electricity that we use at home and school is current. (v) The filament of an electric iron is made up of . (vi) The coil of wire in electric cooker is made up of . (vii) One should look for mark to ensure that an appliance is safe. CHAPTER 7. ELECTRICITY 114

(viii) Wastage of electricity can be reduced by . (ix) The safety device used in electric circuits is . 2. Fill in the blanks. [Refer to Session 7.2 ] (x) The longer line in the symbol for a cell represents its terminal. (xi) The thicker smaller line in the symbol for a cell represents its terminal. (xii) Two or more cells, when joined together, form a . (xiii) is a device used to close or open an electric circuit. 3. State true or false. [Refer to Session 7.3 ] (xiv) In a series circuit, electricity has only one path. [] (xv) In a parallel circuit, electricity has more than one path. [] (xvi) To make a battery of two cells, the negative terminal of one cell is connected to the negative terminal of the other cell. [] (xvii) When the electric current through the fuse exceeds a certain limit, the fuse wire gets over heated and melts. [] (xviii) The switch is used to close or open an electric circuit. [] CHAPTER 7. ELECTRICITY 115

4. Match the following. Column B [(Session 7.3)] a. Bulb doesn’t glow in this circuit Column A i. ii. b. Parallel circuit diagram iii. c. Electric circuit iv. d. Series connection v. e. Parallel connection of cells 5. Answer the following questions in one sentence. [Refer to Session 7.1 ] (xix) How many paths does electricity have in a series circuit? Short Answer Type Questions 6. Answer the following questions in 3-4 sentences. (i) [(Session 7.4)] What are the advantages of using tube lights and CFLs? CHAPTER 7. ELECTRICITY 116

(ii) [(Session 7.4)] What is an electric fuse? (iii) [(Session 7.4)] What is an MCB? (iv) [(Session 7.4)] 5–year–old Tony feels that the glowing of a bulb on pressing the switch is like magic. Do you also find it magical? Why or why not? (v) [(Session 7.4)] What are the inventions of Michael Faraday? (vi) [(Session 7.4)] How does an electric fuse work? 7. Answer the following questions in 3-4 sentences. (i) [(Session 7.3)] Describe the effect of connecting batteries in 1) series 2) parallel. Long Answer Type Questions 8. Answer the following questions in 6-8 sentences. (i) [(Session 7.3)] Differentiate between series and parallel connection. AS2-Asking questions and making hypothesis Short Answer Type Questions 9. Answer the following questions in 3-4 sentences. (i) [(Session 7.4)] Why should an electrician use rubber gloves while repairing an electric switch at your classroom? Explain. Long Answer Type Questions 10. Answer the following questions in 6-8 sentences. (i) [(Session 7.4)] An electrician is carrying out some repairs in a building. He wants to replace a fuse by a piece of wire. Would you agree with the electrician? Give reasons for your response. AS4-Information skills and projects Short Answer Type Questions 11. Answer the following questions in 3-4 sentences. CHAPTER 7. ELECTRICITY 117

(i) [(Session 7.4)] List the factors on which the amount of heat produced in a wire de- pends upon. Long Answer Type Questions 12. Answer the following questions in 6-8 sentences. (i) [(Session 7.4)] Suppose in a house there are four bulbs of 100 W each, six of 60 W each and six of 40 W each. All of them are used for two hours a day. How many units of electricity will be used up in 30 days? How much will they have to pay at Rs. 2.80 /–unit? AS5-Communication through drawing and model making Long Answer Type Questions 13. Answer the following questions in 6-8 sentences. (i) [(Session 7.2)] Radha is given with –a cell, a switch, bulb and wires. Explain with the help of a diagram to connect a circuit. 14. Answer the following questions in 6-8 sentences. (i) [(Session 7.3)] Write an experimental procedure to connect electrical cells in parallel. Draw parallel circuit diagram. 15. Answer the following questions in 6-8 sentences. (i) [(Session 7.1)] Draw and explain the mechanism of a dry cell. AS7-Application to daily life, concern to bio diversity Short Answer Type Questions 16. Answer the following questions in 3-4 sentences. (i) [(Session 7.4)] Why mostly all electrical home appliances like refrigerator, toaster etc. are provided with a wire having green insulation? Long Answer Type Questions 17. Answer the following questions in 6-8 sentences. (i) [(Session 7.4)] Is there a need for our country to save electricity? Explain? CHAPTER 7. ELECTRICITY 118

Objective Questions AS1-Conceptual Understanding 18. Choose the correct answer. (i) Which cell converts chemical energy in to electrical energy? (A) Mobile cell (B) Dry cell (C)Electric cell (D)Carbon cell (ii) What serves as the positive terminal in a dry cell? (A) There is no positive terminal in a dry cell (B) The metal rod with a carbon cap. (C)The carbon (graphite) rod with a metal cap. (D)Aluminium chloride (iii) Which electronic component is used to close or open an electric circuit? (A) Fuse (B) Switch (C) Cell (D) Battery (iv) What happens when two or more cells are joined together? (A) They form a circuit (B) They form a battery (C)They form a switch (D)They form a fuse (v) In a series circuit, how many paths does the electricity have to flow through? (A) No path or zero path (B) Infinite number of paths (C)One path (D)Two paths (vi) How are all the components in our house connected? (A) In series (B) In parallel (C)In perpendicular direction (D) Independently (vii) CFL stands for CHAPTER 7. ELECTRICITY 119

(A) Compact floral Light (B) Connected floral lamp (C)Compact Fluorescent Light (D)Compact Fluorescent Lamp (viii) Which mark ensures the safety of the electrical appliance? (A) CFL (B) MCB (C)Trade mark (D) ISI (ix) Electricity used for which purpose is cheaper? (A) Industrial purpose (B) Commercial purpose (C)Domestic purpose (D)All purpose (x) Which of the following was not invented by Michael Faraday? (A) Transistor (B) Dynamo (C) Transformer (D)Electric generator CHAPTER 7. ELECTRICITY 120

8. AIR, WINDS AND CYCLONES SESSION 1 INTRODUCTION TO AIR AND AIR PRESSURE 1.1 Mind Map 1.2 Terminology i. Air – is the Earth’s atmosphere which is a mixture of many gases and dust particles. It is the clear gas in which living things live and breathe. ii. Wind –refers to the moving air. iii. Pressure – is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. 1.3 Key Concepts i. We feel air all around us, air is present everywhere. ii. An empty object is always filled with air and air occupies space. iii. In order to add anything to an empty object we need to remove an equal amount of air from that object. iv. Being gaseous in nature air exerts pressure. v. Air around us keeps on moving from one place to another. This moving air is known as wind. SESSION 1. INTRODUCTION TO AIR AND AIR PRESSURE 121

1.4 Application to Daily Life, Concern to Bio Diversity Q1. State two experiences that make you think that air exerts pressure (other than those given in the text). [Refer to TB page 79 Q6] A. Activity–1: i. Take a tin can with a lid. ii. Fill nearly half of it with water. iii. Heat the can on a candle flame till the water boils. iv. Remove the candle after the water boils for about 5 minutes. v. Immediately put the lid tightly closing the can. vi. Put the can in a shallow tub. vii. Pour cold water over the can. viii. You observe that the can gets compressed. ix. As water is poured over the can, the steam in the can condenses to water, reducing the amount of air inside. x. The pressure of air inside the can decreases than the pressure exerted by the air from outside the can. xi. As a result the can gets compressed. Activity–2 : i. Crumple a small piece of paper into the shape of a ball. ii. Keep the paper ball inside a wide mouthed bottle such that the ball is just inside its mouth. iii. Blow air on the ball to push it into the bottle. iv. When we blow into the mouth of the bottle, the air near its mouth has higher speed. This decreases the pressure there. v. The air pressure inside the bottle is higher than near its mouth. vi. So the air inside the bottle would not let the ball in. vii. This is another example to show that air exerts pressure. SESSION 1. INTRODUCTION TO AIR AND AIR PRESSURE 122

SESSION 2 AIR EXPANDS ON HEATING 2.1 Mind Map 2.2 Terminology i. Air – is the Earth’s atmosphere which is a mixture of many gases and dust particles. ii. Pressure – is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. iii. Expansion –Heating causes air to occupy more space, such that it becomes less dense but exerts higher pressure. This is called expansion of air. iv. Sea breeze –Gentle breeze blowing into the land from the sea due to faster heating of land by the Sun during the day. v. Land breeze – Gentle breeze blowing out to the sea from the land due to faster cooling of the land during night. 2.3 Key Concepts i. Air is a mixture of several gases. ii. Even though the air is invisible, it actually takes up space and has weight. iii. Air is affected by temperature or heat. It expands on heating and contracts on cooling. iv. As the air expands it occupies greater space and becomes less dense. v. The greater the temperature, the faster the air particles move (increasing pressure), so warm air is lighter than cold air. SESSION 2. AIR EXPANDS ON HEATING 123

vi. Air moves from a region of high pressure to a region of low pressure. vii. Speed of moving air is dependent on difference in the air pressure between two re- gions. viii. Differential heating of earth’s surface (land and water) by sun causes land and sea breeze. 2.4 Conceptual Understanding Q1. Fill in the blanks: [Refer to TB page 79 Q3] Near the earth’s surface, air rises up whereas air comes down. A. Near the earth’s surface, hot air rises up whereas cool air comes down. Q2. While a constructing house, where do we construct ventilators? Why? [Refer to TB page 80 Q7] A. While constructing a house, we construct ventilators above the doors and windows. Reason: i. The fresh air enters the house through doors and windows. ii. After being used for respiration, the expired air is warm and moist. iii. This warm air rises up and escapes through the ventilators lying above the doors and windows. iv. In this way, it does not obstruct the fresh air coming from doors and windows. Q3. In daytime, when we go to the sea shore the air blows towards us and does not go towards the sea. Explain. [Refer to TB page 80 Q10] A. i. During daytime, the land heats up faster than the water in the sea. ii. Warm air rises over the land and creates a low pressure and the cool air over the sea blows towards the land to occupy the space left by hot air. iii. This happens as movement of air takes place from high pressure to low pressure. iv. So, the air blows towards us and does not go towards the sea. SESSION 2. AIR EXPANDS ON HEATING 124

SESSION 3 EFFECTS OF MOVING AIR AND WIND 3.1 Mind Map SESSION 3. EFFECTS OF MOVING AIR AND WIND 125

3.2 Terminology i. Wind – refers to the moving air. ii. Low pressure –is a condition of the atmosphere in which the pressure is below aver- age, ie., in a depression, which almost always cause rain. iii. High pressure –is a condition where the atmospheric pressure at the surface of the planet is greater than its surrounding environment. It causes outward flow of winds to areas of lower pressure. iv. Monsoon winds –are winds flowing from the ocean to lands during the months of June to September. 3.3 Key Concepts i. Wind move from one region to other due to uneven heating of the earth. ii. Different regions of the earth get heated up differentially by the sun. iii. Regions near equator receive more heat and are warmer as they receive direct sun- light for more duration. iv. Warm air being lighter rises up and cool air being heavier tends to descend towards the earth’s surface. v. The rising up of warm air causes decrease in air pressure of that area and space thus formed is filled up by cooler air. vi. In the months of June to September, monsoon winds blow near the equator from oceans to land due to faster heating of land than water in the ocean. vii. The direction of wind gets reversed from land to sea during the winter months of December to early March. viii. The monsoon winds from oceans carry water and bring rains which are useful for farmers for their harvests. ix. Winds also bring down earth’s temperature. x. High–speed winds are useful in the generating electricity. 3.4 Conceptual Understanding 126 Q1. Fill in the blanks: SESSION 3. EFFECTS OF MOVING AIR AND WIND

i. Wind is air. [Refer to TB page 79 Q1] ii. Winds are generated due to heating on the earth. (TB Pg79; Q2) iii. Air moves from a region of pressure to a pressure. (TB Pg79; Q4) A. i. Wind is moving air. ii. Winds are generated due to uneven heating on the earth. iii. Air moves from a region of high pressure to a low pressure. Q2. Suggest two methods to find out wind direction at a given place. [Refer to TB page 79 Q5] A. Method 1: The direction of wind at a place can be determined by using an anemometer. Method 2: Tie an inflated balloon at the end of a thread. i. Hold the free end of the thread in your hand and stand in the open air. ii. The direction in which the balloon flies indicates the direction of wind. Q3. Explain why holes are made in banners and hoardings hanging in the open. [Refer to TB page 80 Q8] A. i. We know that air is not stationary and moves at different speeds depending on the difference in pressure of two areas. ii. If there were no holes in banners and hoardings hanging in the open, the air blow- ing will be obstructed by the banner. iii. This would create a high pressure which may cause tilting of the banner due to which the writings on the banner will not be visible to the passersby. iv. Thus, holes are made which allows the air to escape through them and the banner or hoarding stays in place. Q4. Which of the statements given below is correct? [Refer to TB page 80 Q11] a) In the winter, the winds flow from land to the ocean. b) In summer, the winds flow from the land towards the ocean. SESSION 3. EFFECTS OF MOVING AIR AND WIND 127

A. a) Correct b) Incorrect 3.5 Experimentation and Field Investigation Q1. Read the following procedure and make your own anemometer. [Refer to TB page 80 Q12] Collect the following items: (a) 4 small paper cups (b) Two strips of cardboard measuring 20 cm long, 2 cm width (c) Gum (d) Stapler (e) Sketch pen (f) Sharpened pencil. i. Take a scale and draw crosses under the card board strips as shown in the figure. ii. Fix the strips at the centre, putting one over the other such that they make a ‘+’ sign. Now fix the cups at the ends of the strips. iii. Colour one cup with sketch pen. All four cups should face in the same direction. iv. Push a pin through the centre of the strips and attach the strips to the sharpened pencil. v. Check that the strips rotate freely and when you blow on the cups. Your anemome- ter is ready. vi. Counting the number of rotations for a minute will give you an estimate of the speed of the wind. A. Students’ Activity 128 SESSION 3. EFFECTS OF MOVING AIR AND WIND

Q2. More fun with air. [Refer to TB page 80 Q15] A. Do the following activities and write your findings i. Take an empty bottle and place it on the table as shown in the figure above. Place a cotton ball just inside its mouth. ii. Now try to blow air on the ball to send it into the bottle, and then try the activity with bottles of different sizes. iii. Throw a challenge to your friends whether they can send the cotton ball inside the bottle by blowing air. iv. Are you surprised? Why did this happen? Think about it and discuss with your friends. B. Can you blow out the ball from funnel? i. Take a funnel and ball, keep the funnel in your mouth as shown in the figure above. ii. Keep the ball in the funnel. Blow air through the funnel and try to send out the ball from the funnel. iii. What happens? Have you succeeded in sending the ball out? SESSION 3. EFFECTS OF MOVING AIR AND WIND 129

And then place the ball on your hand and put the funnel over the ball as shown in the figure above. Now blow air forcefully through the funnel and try to blow out the ball from the funnel (while blowing air, remove hand). i. What did you observe? ii. What did you expect? iii. What happens? iv. Try to answer and discuss with your friends. C. Flow of air i. Take a large plastic bottle and a two–holed rubber cork that fits firmly into its mouth. ii. Also take two glass tubes. Tie a coloured balloon to the lower end of one of the glass tubes. iii. Insert the glass tubes into the two holes of the cork. The glass tubes should fit tightly in the holes. iv. Close the mouth of the bottle with the cork and seal it with sealing wax to make the bottle airtight. v. The balloon should be inside the bottle as shown in the figure above. Now suck air out of the bottle through the tube that doesn’t have a balloon attached to it. vi. What happens to the balloon? Why do you think this happened? SESSION 3. EFFECTS OF MOVING AIR AND WIND 130

A. A. i. Blowing air at the mouth of the bottle results in lowering of air pressure there. ii. The pressure of the air inside the bottle becomes higher than outside. iii. So, the air from inside the bottle tends to rush out to occupy the area of low pres- sure, thus exerting pressure on the cotton ball. iv. This prevents the ball from going in the bottle. B. i. In the first case, if the ball is light enough, and you blow air forcefully, it gets thrown out of the funnel. ii. Else, it jumps up and down in the funnel. iii. In the second case, if you blow air, the ball will fall down due to gravity as well as pressure of the air. iv. However, if you suck hard on the funnel, the ball will stick to the funnel and not fall down. C. i. As air is sucked out of the bottle, the pressure inside decreases. ii. This causes the air at higher pressure present outside to rush in through the other rod. iii. And, the balloon expands inside the bottle. SESSION 3. EFFECTS OF MOVING AIR AND WIND 131

SESSION 4 CYCLONES 4.1 Mind Map 4.2 Terminology i. Cyclones –are a form of violent storms on Earth. In meteorology, they refer to any low pressure area with winds spiraling inwards. ii. Typhoon – is a mature tropical cyclone that develops in the western part of the North Pacific Ocean in the region referred to as the Northwestern Pacific Basin. iii. Hurricane –is another name for cyclones. iv. Tropical cyclone –is a rapidly rotating storm system characterized by a low–pressure center, strong winds, and a spiral arrangement of thunderstorms that produce heavy rain. v. Anemometer –is the instrument used to measure wind speed. 4.3 Key Concepts i. Cyclones are referred to as large, violent, destructive storm with very high winds that turn around an area of low pressure. SESSION 4. CYCLONES 132

ii. Factors like wind speed, wind direction, temperature and humidity initiate the devel- opment of cyclones. iii. Cyclones are very destructive and the amount of destruction caused by a cyclone depends upon its intensity, size and location. iv. In India, the months of May–June and October–November are cyclone prone months. v. During cyclones, we should not ignore warnings by meteorological department through T.V., radio or newspapers and take necessary precautions. vi. On the other hand, we should not panic rather we should cooperate and help other fellow beings to overcome the situation. 4.4 Conceptual Understanding Q1. Which of the statements given below is correct? [Refer to TB page 80 Q11](c), (d)) (c) A cyclone is formed by a very high pressure system with very high speed winds revolving around it. (d) The coastline of India is not vulnerable to cyclones. A. (c) Incorrect (d) Incorrect 4.5 Information Skills and Projects Q1. Interview eye witnesses to collect the actual experiences of people affected by a cyclone. [Refer to TB page 80 Q14] A. Students’ Activity Q2. Collect some articles and photographs from newspapers and magazines about storms and cyclones. Make a story on the basis of what you learnt in this chapter. [Refer to TB page 80 Q13] A. Students’ Activity (Students can collect some pictures of cyclone affected areas from newspaper and cre- ate a storyline supporting their pictures) SESSION 4. CYCLONES 133

4.6 Application to Daily Life, Concern to Bio Diversity Q1. How will you help your neighbours in case cyclone approaches your village or town? [Refer to TB page 80 Q9] A. i. I will watch the T.V. or listen to the radio for the report issued by the meteorological department and pass it on to my neighbours. ii. I will try to make necessary arrangements to shift the essential household goods, domestic animals and vehicles etc. to safer places. iii. I will help the elders, shift babies and old people who cannot run away to safer place. iv. I will keep the telephone numbers ready of essential services such as the police, the fire brigade, medical service and the revenue authorities. v. I will see that my neighbours are shifted to cyclone relief centers and to refugee centers started by Red Cross, Rotary Clubs and Lions Clubs. —— CCE Based Practice Questions —— AS1-Conceptual Understanding Very Short Answer Type Questions 1. Answer the following questions in one sentence. [Refer to Session 8.4 ] (i) What are cyclones? (ii) What factors contribute to the development of cyclones? (iii) During which months do cyclones occur in India? (iv) What are the main effects of cyclones? (v) What does IMD stand for? CHAPTER 8. AIR, WINDS AND CYCLONES 134

2. State true or false. [ ] [Refer to Session 8.1 ] [ ] [ ] (vi) The air around us is always still. [ ] [ ] (vii) The movement of air is called wind. ] (viii) Air is present only in restricted places. (ix) Nothing can be added to a container until air is added. (x) Air occupies the space around us. 3. Fill in the blanks. [Refer to Session 8.3 ] (xi) Uneven heating of earth causes . (xii) The moving air creates presssure. (xiii) Direction of sunlight is more direct as it gets closer to the . (xiv) Monsoon winds usually occur during the months of to . (xv) The direction of wind flow gets usually reversed in the months from to early . 4. State true or false. [Refer to Session 8.2 ] (xvi) Warm air always settles down. [ CHAPTER 8. AIR, WINDS AND CYCLONES 135

(xvii) When something occupies more space, it becomes less dense. (xviii) When air rises up, air pressure become high. [ ] [ ] (xix) Land heats up faster than sea. [ ] [ ] (xx) At night, sea cools faster than land. 5. Fill in the blanks. [Refer to Session 8.2 ] (xxi) Air on heating. (xxii) Hot air is than cold air. (xxiii) Air travels from areas of pressure to pressure. (xxiv) The greater the difference in pressure, the the air moves. (xxv) Warm air is dense than cold air. Short Answer Type Questions 6. Answer the following questions in 3-4 sentences. (i) [(Session 8.4)] What are cyclones? What are its other names? 7. Answer the following questions in 3-4 sentences. (i) [(Session 8.1)] Why cannot you add anything to something until air is removed? 8. Answer the following questions in 3-4 sentences. (i) [(Session 8.3)] Why does the region close to equator get more heat? (ii) [(Session 8.3)] How does cooler air move towards the equator? 9. Answer the following questions in 3-4 sentences. (i) [(Session 8.2)] What happens when you take an inflated balloon and heat it slowly? CHAPTER 8. AIR, WINDS AND CYCLONES 136

(ii) [(Session 8.2)] What happens when the tied end of a balloon is opened? Why? Long Answer Type Questions 10. Answer the following questions in 6-8 sentences. (i) [(Session 8.4)] Write any four do’s and don’ts during cyclones. (ii) [(Session 8.4)] Write short notes on formation of cyclones. AS2-Asking questions and making hypothesis Long Answer Type Questions 11. Answer the following questions in 6-8 sentences. (i) [(Session 8.3)] Anil was sitting in the balcony. From there, he could smell biryani that was cooking in his neighbour’s house. He wondered why he could not smell the biryani that was in the fridge in his house. What questions could have come in Anil’s mind? AS3-Experimentation and field investigation Short Answer Type Questions 12. Answer the following questions in 3-4 sentences. (i) [(Session 8.1)] What happens to the crushed paper when placed in a glass and in- verted into a bucket of water keeping the glass straight? Justify. (ii) [(Session 8.1)] What do you observe when you immerse a bottle in a bucket filled with water? Why do you think this happens? (iii) [(Session 8.1)] What are the three steps to use a dropper? Long Answer Type Questions 13. Answer the following questions in 6-8 sentences. (i) [(Session 8.1)] Suggest an experiment to show that any container that appears empty is also filled with air. CHAPTER 8. AIR, WINDS AND CYCLONES 137

14. Answer the following questions in 6-8 sentences. (i) [(Session 8.2)] How will you show that hot air is lighter than cold air? AS4-Information skills and projects Long Answer Type Questions 15. Answer the following questions in 6-8 sentences. (i) [(Session 8.4)] Collect information about recent cyclone–hit places in India and the destruction caused by those cyclones. AS5-Communication through drawing and model making Long Answer Type Questions 16. Answer the following questions in 6-8 sentences. (i) [(Session 8.1)] Observe the following image and explain what you understand by the image. AS7-Application to daily life, concern to bio diversity 138 Short Answer Type Questions 17. Answer the following questions in 3-4 sentences. (i) [(Session 8.4)] Give any three post cyclone measures. CHAPTER 8. AIR, WINDS AND CYCLONES

Objective Questions AS1-Conceptual Understanding 18. Choose the correct answer. (i) Moving air is called . (A) storm (B) wind (C) pressure (D) cyclone (ii) Air in these regions are warmer. (A) Poles (B) Latitude (C) Equator (D) Altitude (iii) Cyclones are a form of . (A) pleasant wind (B) heavy rain (C)violent storms (D)high tide (iv) An empty container is always . (A) empty (B) filled with water (C)filled with air (D)none of the above (v) Increased wind speed is accompanied by (A) increased air pressure (B) decreased air pressure (C)no change in air pressure (D)none of the above (vi) Nothing can be added to a container until (A) it is filled with that substance (B) air is removed (C)water is added (D)the substance is light CHAPTER 8. AIR, WINDS AND CYCLONES 139

(vii) During the months of May–June or October–November, we can see the reports of this natural calamity. (A) Earthquake (B) Acid rain (C) Cyclone (D) Drought (viii) Indian cyclones usually occur in the months of (A) Jannuary–February and June–July (B) March–April and November–December (C)June–July and October–November (D)May–June and October–November (ix) What happens to a balloon when excess air is filled into it? (A) It contracts (B) It expands (C)It bursts (D)It remains same (x) The air over the land gets heated and rises. This results in flow of winds from (A) ocean to land (B) land to ocean (C)both a and b (D)none of the above (xi) Air is present . (A) in high lying areas (B) in low lying areas (C)in flat areas (D) everywhere (xii) We can generate this from high speed winds. (A) Rain (B) Cyclone (C) Electricity (D) Heat (xiii) The instrument that measures wind speed is called (A) seismograph (B) tide gauge (C)rain gauge (D) anemometer CHAPTER 8. AIR, WINDS AND CYCLONES 140

(xiv) leads to expansion of air. (A) Heating (B) Cooling (C) Pressing (D) Volume (xv) Hot air is than cold air. (A) heavier (B) lighter (C) smaller (D) bigger (xvi) Information about cyclones are given by the . (A) DMI (B) MID (C) IMD (D) IDM (xvii) may be caused due to wind travelling at high speed due to difference in air pressure. (A) Rains (B) Cyclones (C) Volcanoes (D) Tsunamis (xviii) The destruction of a cyclone depends mainly on its . (A) intensity (B) size (C) location (D)all the above (xix) Cyclones are characterized by the presence of . (A) heavy rain and strong winds (B) pleasant weather and light rains (C)light rain and winds (D)hot weather and dusty winds (xx) A cyclone alert is issued hours in advance of any expected storm and a cyclone warning is issued hours in advance. (A) 48, 24 (B) 24, 48 (C)15, 42 (D)30, 24 CHAPTER 8. AIR, WINDS AND CYCLONES 141

PROJECT BASED QUESTIONS —— Project Based Questions —— (i) While several foods are rich in iron, many people have trouble getting enough in their diet. That is why chemical food engineers sometimes add iron to processed food such as cereals. What is your opinion about the statement –“The irons in our cereal is the same iron that is attracted to magnet”. Make a project report on the above mentioned statement and also mention in your report that why is iron important part of the human diet. (ii) Acids and bases are important factors in natural system, such as the human body. Make your research and make a report relating the importance of acid and bases to environment such as lakes, rivers and oceans as well as environmental engineering concerns. Also include in your report the list of several things that environmental engineers are doing to reduce acid rain and its effect. (iii) Make a project report on the fabric qualities that you think are the most important for durability of the fabric. (Hints–The type of fibre in the thread , strength of the thread, type of tightness of the weave etc). Also collect pictures of various types of fabric of your knowledge from internet or magazines and paste it on the front page of your report booklet to make it more presentable. (iv) ”It was study of physics and Galileo’s experiment with pendulum that made pendulum clock possible”. Write an article on the above statement taking help from internet, science magazines and library book. Also mention examples of how engineers use pendulum nowadays in your article. (v) Make a scrap book explaining why engineers design different types of home in differ- ent locations. Collect pictures of different home designs and patterns that engineers use for different climates (Hint–Thick wall for desert climate, peaked roof for snowy areas, elevated foundation for tropical climates etc) and paste those pictures in your scrap book under suitable titles or headings. (vi) To check if your body has a fever, your parents or a medical practitioner uses a clinical thermometer. If you want to make your own thermometer what would be the proce- dural steps. Make a research with the help of internet or science books to make your own thermometer and write up your research in a small booklet. Project Based Questions 142

PROJECT BASED QUESTIONS (Caution–Research for procedural steps is only needed. Students are not asked to design a thermometer at home as this activity demands expert supervision). (vii) Electrical engineers continuously evolve technology to improve the performance and life cycle cost of batteries that store solar energy and wind energy. Taking help from library books or internet make a report on the role of electrical engineers in the devel- opment of electricity sources and products that use electricity. (viii) Make a project report on where electricity comes from and how do we use it. Also define electrical energy in terms of charge, voltage, current and resistance. Investi- gate where at your home electricity might be excessively used. Mention at least two possible ways to conserve electricity. (ix) Take help from books in your school library and internet and write a note on cyclones that affected Andhra Pradesh in the recent years with special reference to cyclone Laila of 2010, and cyclone Hudhud of 2014. Also write a note on the preparations and impact of these cyclones. Project Based Questions 143

Additional AS- Based Practice Questions Chapter 1: Food Components Q1. Read the statement below and answer the given questions. (AS4) “Raju tested a food sample with iodine and he observed that the sample turned blue black in colour” i. Why he got blue black colour after adding iodine? ii. Name some other food items that may show similar reaction with iodine. Q2. Draw diagrams of food items that are rich source of water. (AS5) Q3. Rahul was advised not to eat junk food by his doctor. Explain why junk foods are not good for our health. (AS7) Q4. Appreciate the role of proteins in our body. (AS6) Q5. “James Lind played a great role in understanding health and nutrition”. How can you justify this statement? (AS6) Chapter 2: Acids and Bases Q1. What is the cause of tooth decay? (AS7) Q2. Give two important uses of washing soda and baking soda. (AS6) Q3. A milkman adds a very small amount of baking soda to fresh milk. (AS6) (a) Why does he shift the pH of the fresh milk from 6 to slightly alkaline? (b) Why does this milk take a long time to set as curd? Q4. With the help of flowchart describe different types of salts. (AS5) Q5. Classify given substances as acid and base. (AS4) Sugar, Tomato, Washing powder, Tooth paste, Toilet cleaner (Harpic), Dettol Q6. (AS5) i. Which gas is passed through the tube A? ii. What are your observations? A iii. What is present in the test tube labelled as B? B Additional AS-Based Practice Questions 144

Chapter 3: Animal Fibre Q1. On a chilled winter day Rita wore a red sweater over her cotton dress. Why she wore the sweater even though she had a cotton dress? Provide suitable reason for this. (AS2) Q2. What are the main hazards of silk industry? (AS7) Q3. We find a number of varieties of silk in the market. How do we get those varieties of silk? (AS6) Q4. On seeing a person caught in fire, Rajat wrapped him quickly in a woollen blanket. Appreciate the effort of Rajat in doing so. (AS6) Q5. What is shown in the diagram below? Describe the process in brief. (AS4) Chapter 4: Motion and Time Q1. Draw a diagram of simple pendulum. What kind of motion does it show? (AS5) Q2. If your car takes 20 minutes to reach your school which is 15 km away from your home, then what is the speed of your car in Km/hr? (AS7) Q3. Draw a flowchart showing different types of motion. (AS5) Q4. Observe and think of different living and non- living things in motion at your home and list the type of motion they show. Record your observation in tabular form. (AS3) Q5. How do you appreciate the use of watch in our lives? (AS6) Chapter 5: Temperature and its Measurement Q1. Have you ever been to a doctor? If you see a clinical thermometer it ranges from 35oC to 42oC. Find the reason why is it so? (AS7) Q2. Write down the importance of the m a x i m u m - m i n i m u m thermometer? (AS6) Q3 .Draw the relation between Celsius, Fahrenheit and Kelvin scales? How are they interrelated? (AS6) Q4 . (AS5) 1. Which activity is shown in the diagram? 2. What are the apparatus used? 3. What will happen if you take the flask out of the trough and keep it outside for some time? Chapter 7: Electricity; Current and its Effect Q1. Sonali used same fuse in geyser and a television set? Did she do the right thing? Justify your answer. (AS2) Additional AS-Based Practice Questions 145

Q2. An electric bulb has figure 220 V and 100 W written on it. What does it mean? (AS4) Q3. Why the consumption of electricity is increasing in recent time? (AS6) Q4. Zubeda made an electric circuit using a cell holder shown in Figure below, a switch and a bulb. When she put the switch in the ‘ON’ position, the bulb did not glow. Help Zubeda in identifying the possible defects in the circuit. (AS3) Q5. Describe the steps involved in making a parallel circuit. (AS3) Q6. Write down the contributions of Michael faraday. (AS6) Chapter 8: Air, Winds and Cyclones Q1. To expel hot air out of kitchen ‘A’ has an exhaust fan fitted on the window of her kitchen while ‘B’ has a similar fan on the wall near ceiling of her kitchen. Which of the exhaust fan will expel hot air more effectively and why? (AS2) Q2. Suggest some precautions to be taken to prevent the roof of a tin sheet from flying away during heavy wind or storm? (AS7) Q3. Identify the names of six natural phenomenon from the following word puzzle. (AS4) Q4. While passing by a railway track Rita’s mother advised her not to stand near fast moving train? How will you appreciate her decision? (AS6) Q5. Explain land breeze with a diagram. (AS5) Q6. What planning is required in advance to deal with the situation created by a cyclone? (AS6) i. What is the aim of the experiment shown in the diagram? ii. What apparatus are required to conduct the experiment? iii. Can we use bricks instead of paper cups in this experiment? Additional AS-Based Practice Questions 146