202110222-TRIUMPH-STUDENT-WORKBOOK-SCIENCE-G06-PART2

16. Answer the following questions in 6-8 sentences. (i) [(Session 13.4)] Suggest some ways of measuring the volumes of the following: (i) Irregular solids. (ii) Kerosene (iii) Loose solids like dices CHAPTER 13. LEARNING HOW TO MEASURE 49

AS7-Application to daily life, concern to bio diversity Long Answer Type Questions 17. Answer the following questions in 6-8 sentences. (i) [(Session 13.4)] List out some conventional ways for rough measurements in our daily life. Discuss if all of them can be used for measuring different objects with different shapes and volumes. Objective Questions 50 AS1-Conceptual Understanding 18. Choose the correct answer. (i) One centimeter is equal to CHAPTER 13. LEARNING HOW TO MEASURE

(A) 100 mm (B) 10 mm (C)1.0 mm (D)0.1 mm (ii) Which measuring unit is used to measure larger distances? (A) Centimetre (B) Kilometre (C) Metre (D)All of the above (iii) How did people measure lengths of different objects before measuring instruments were invented? (A) By using hands (B) By using foot (C)By using palm (D)All of the above (iv) In olden days, the distance between nose and tip of the middle finger of the king of a particular kingdom was called as _____________. (A) One yard (B) One metre (C) Kilometre (D) Millimetre (v) Which instrument will you use to measure the thickness of an eraser? (A) Hands (B) Plain tape (C)Rolled tape (D)Centimetre scale (vi) A measure of extent of space is called as (A) Area (B) Volume (C) Weight (D) Distance (vii) What is the standard unit of measuring the area of a surface? (A) m2 (B) mm2 (C) ft2 (D) cm2 CHAPTER 13. LEARNING HOW TO MEASURE 51

(viii) The measure of the extent of plane surface occupied by an object is called as ___________________. (A) Area (B) Volume (C) Distance (D) Mass (ix) What is the standard unit of length? (A) Centimetre (B) Metre (C) Kilometre (D) Millimetre (x) When did The Republic of India adopt the metric system? (A) 2nd May 1947 (B) 1st April 1957 (C)15th August 1947 (D)26th January 1950 CHAPTER 13. LEARNING HOW TO MEASURE 52

14. MOVEMENTS IN ANIMALS SESSION 1 HUMAN BODY AND ITS MOVEMENT, MUSCLES 1.1 Mind Map 1.2 Terminology i. Muscle – A bundle of fibrous tissue in a human or animal body that has the ability to contract, producing movement in or maintaining the position of parts of the body. ii. Ligament – A short band of tough, flexible fibrous connective tissue which connects two bones or cartilages or holds together a joint. iii. Tendon –The fibrous tissue attaching a muscle to a bone. iv. Contraction –The process in which a muscle becomes or is made shorter and tighter. v. Expansion –The action of becoming larger or more extensive. 1.3 Key Concepts i. We are able to make body movement with the help of bones, musles and joints. ii. These bones and muscles are present beneath our skin that protects them. iii. We cannot see our bones and muscles but we can get a sense of their movements under our skin. SESSION 1. HUMAN BODY AND ITS MOVEMENT, MUSCLES 53

iv. Muscles help the various parts of the body to move or maintaining the position of parts of the body. v. When muscle contracts it becomes shorter, stiffer and thicker. vi. Muscles work in pairs and bring about movement by contraction and relaxation. 1.4 Application to Daily Life, Concern to Bio Diversity Q1. What is this instrument? ‘How do you use this? [Refer to TB page 151 Q12] A. 1) This instrument is a Dumb–bell. 2) Dumb-bell is used for exercising the muscles in the upper arm. 3) It is taken in one of the hands and is raised and lowered repeatedly for exercising. SESSION 1. HUMAN BODY AND ITS MOVEMENT, MUSCLES 54

SESSION 2 BONES, TYPES OF JOINTS 2.1 Mind Map SESSION 2. BONES, TYPES OF JOINTS 55

2.2 Terminology i. Bones –The pieces of hard whitish tissue making up the skeleton in humans and other vertebrates. ii. Joints – A structure in the human or animal body at which two parts of the skeleton are fitted together. iii. Clavicle –Collar bone. iv. Jaw bone – A bone of either jaw. v. Ribs –A series of curved bones that are articulated with the vertebrae and occur in pairs. vi. Backbone –The series of vertebrae extending from the skull to the pelvis; the spine. vii. Vertebrae – Each of the series of small bones forming the backbone. viii. Spinal cord –The cylindrical bundle of nerve fibres and associated tissue which is enclosed in the spine and connects nearly all parts of the body to the brain. ix. Pelvic girdle – The enclosing structure formed by the bony pelvis, providing attach- ment for the hindlimbs or pelvic fins. x. Cartilage – Flexible bone found in structures such as the external ear, and in the articulating surfaces of joints. xi. Ball & socket joint – A joint in which a ball moves within a socket so as to allow rotary SESSION 2. BONES, TYPES OF JOINTS 56

motion in every direction within certain limits. xii. Hinge joint – Hinge joints are formed between two or more bones where the bones can only move along one axis to flex or extend. xiii. Neck joint – This joint helps us to move our head up–down and side to side. xiv. Fixed joint – These joints are also called as ”immovable” joints, because they do not move. 2.3 Key Concepts i. Two bones are joined together in a special way by fibres. These fibres are called ligaments. ii. The spinal cord passes through the vertebrae of the backbone. iii. There are 33 separate vertebrae in the backbone of an infant. iv. Some parts of the ear and nose are soft and others that are hard are made up of cartilage. v. Bones of our body move in their own way. vi. The framework of bone, cartilage, or other rigid material supporting or containing the body is called skeleton. vii. Joints are the structure in the human or animal body at which two parts of the skeleton are fitted together. viii. Joints can be classified based on the type of movement they bring about. ix. There are different kinds of joints in our body like ball and socket, hinge, pivotal, gliding joint etc. x. Bones and muscles help us perform different movements and activities. xi. Muscles are attached to bones by tough cords called as tendons. xii. The spine, or backbone, protects the spinal cord, which is the message pathway between the brain and the body.The spine or the backbone is made of many small bones and act like a spring. 2.4 Conceptual Understanding Q1. Imagine a situation where you have no bone in your body. Describe with reasons what would happen. [Refer to TB page 151 Q1] A. i. The body cannot have a shape in the absence of bones. SESSION 2. BONES, TYPES OF JOINTS 57

ii. The skeletal system provides mechanical strength and shape to the body, thus along with no shape, there will not be any mechanical strength as well. iii. We would just feel like a mass of muscles and would not be able to perform any of our day to day activities. Q2. ‘Try and identify the joints in the body of a goat or a cow. Make a list of these joints. [Refer to TB page 151 Q2] A. The following joints are found in the body of a cow: i. Atlas joint ii. Hip joint iii. Stifle joint iv. Tarsal joint v. Fetlock joint vi. Pastern joint vii. Elbow joint viii. Shoulder joint Q3. What is a ball and socket joint. How it is different from hinge joint? [Refer to TB page 151 Q4] A. i. A joint made by fitting a ball into a socket is called a ball and socket joint. ii. In this joint, the bone can rotate easily in all directions. Eg: Joints between the shoulder blades. iii. On the other hand, at a hinge joint, the bone cannot rotate in all directions. iv. The movement at a hinge joint is only in a fixed direction. Eg: Elbow joint. Q4. Fill in the blanks and give reasons: [Refer to TB page 151 Q5] 1. Joints of the bone help in of the body parts. 2. The contraction of the pulls the bones during movement. 3. The bones at the elbow are joined by a joint. SESSION 2. BONES, TYPES OF JOINTS 58

A. 1. Movement 2. Muscle 3. Hinge Q5. Guess who am I? [Refer to TB page 151 Q6] a) I am a joint that works like joint of doors and window. b) I help to join two bones. c) Joint between upper jaw and skull. d) I am a chain of small–small bones. e) I join bone and muscle. A. a) Hinge joint b) Ligaments c) Fixed Joint d) Backbone e) Tendons 2.5 Asking Questions and Making Hypothesis Q1. What difficulties would you face if your fingers had only a single bone? [Refer to TB page 151 Q3] A. If our fingers had only a single bone, then: 1) Writing with our fingers would become impossible. 2) Fingers would fail to catch hold of any object. 3) All the activities for which we use our hands would become very difficult to do. Q2. Prepare a questionnaire to take interview of a yoga teacher or PET sir about asanas and exercises. [Refer to TB page 151 Q8] A. The following questions may be asked: SESSION 2. BONES, TYPES OF JOINTS 59

i. What are the advantages of the Asanas and exercises? ii. When is the best time for doing these exercises or asanas? iii. Would practising asanas and exercises cause any pains in the bones and mus- cles? iv. How long does it take to learn these asanas? v. Would stopping doing these asanas after some time affect our body and health in any way? Q3. Imagine a situation where you have no bone in your body. Describe with reasons what would happen. [Refer to TB page 151 Q1] A. i. The body cannot have a shape in the absence of bones. ii. The skeletal system provides mechanical strength and shape to the body, thus along with no shape, there will not be any mechanical strength as well. iii. We would just feel like a mass of muscles and would not be able to perform any of our day to day activities. 2.6 Information Skills and Projects Q1. Collect X–Ray films and identify which body parts they represent. Write a note on them. [Refer to TB page 151 Q7] A. 1) The student can visit any nursing home and can collect X–ray films or browse the internet and get the images of x-rays of the different parts and identify them One example is given here :. X ray of the palm SESSION 2. BONES, TYPES OF JOINTS 60

2.7 Application to Daily Life, Concern to Bio Diversity Q1. List out the activities that you performed at your home before coming to school. Which joints are involved in each activity? [Refer to TB page 151 Q10] A. The list of activities that I performed before coming to school and the joints involved in each one of them are as following: 1) I brushed my teeth : Joints involved –The hinge joints of my hands and fingers, the fixed joint of the lower jaw and the ball and socket joint at the shoulder. 2) I had my bath : Joints involved –The hinge joint at my elbow, the ball and socket joint at shoulder and the gliding joint of my back bone when I bend myself to apply soap on my feet and ankle. 3) I had my breakfast : Joints involved –While taking my breakfast, I bring my right hand to my mouth. This is done with the hinge joints at the elbow, wrist and fingers. Chewing and gulping food is taken care by the movement of lower jaw. 4) Walked to my school : Joints involved –While walking I use my legs. The ball and socket joint at the girdle and the hinge joint at the knees help in locomotion and thus, help me to walk. Q2. Which joints are involved in plucking flowers, making garlands” Ravi’s mother asked? What is the answer? [Refer to TB page 151 Q11] A. (1) While plucking flowers, the fingers of my hand, the hand and arms are under movement. So, hinge joints between the finger bones and arm; hinge joint at the elbow of hand; and ball and socket joint at the shoulder are involved in the movement. (2) While making garlands, the fingers have to be used and the hands should move. So, the hinge joints at the fingers and arm; and the hinge joints at the elbow are responsible for motion. SESSION 2. BONES, TYPES OF JOINTS 61

SESSION 3 LOCOMOTION, LOCOMOTION IN FISH 3.1 Mind Map 3.2 Terminology i. Locomotion – Movement or the ability to move from one place to another. ii. Streamlined – Design that presents very little resistance to the flow of air or water, increasing speed and ease of movement. SESSION 3. LOCOMOTION, LOCOMOTION IN FISH 62

iii. Perching –To rest on something. iv. Crawling –Move forward on the hands and knees or by dragging the body close to the ground. 3.3 Key Concepts i. Movement of animals is called locomotion. ii. Different animals have different parts of locomotion. iii. The body of the fish is streamlined. iv. Bird’s bones are hollow and light. v. Birds can fly because their bodies have hollow bones and the fore limbs are modified into wings. vi. A cow or buffalo runs on its legs. vii. A fish has fins for its locomotion. viii. A snake has scales all over its body which help in its movement. ix. A snail moves on a strong muscle called foot. x. Movement or locomotion is an important function in every living organism. 3.4 Appreciation and Aesthetic Sense, Values Q1. Crawling snake, jumping frog, flying bird –are they amazing to you? Why do you think so? [Refer to TB page 151 Q9] A. i. Each of these animals show different movements. ii. They are all land animals, but look so different and move so differently. iii. The body structure of these animals is designed in a manner to help in easy move- ment. iv. The bones and muscles developed in their bodies aid in movement and help them to get their food. SESSION 3. LOCOMOTION, LOCOMOTION IN FISH 63

—— CCE Based Practice Questions —— AS1-Conceptual Understanding Very Short Answer Type Questions 1. Answer the following questions in one sentence. [Refer to Session 14.1 ] (i) What happens when muscles are contracted? (ii) What are tendons? (iii) What are the factors on which our body movements depend? (iv) Which are the different parts of the body where we can feel tendons? CHAPTER 14. MOVEMENTS IN ANIMALS 64

(v) How do muscles work in pairs? 2. Fill in the blanks. [Refer to Session 14.1 ] (vi) We can perform different types of movements with the help of and . (vii) Tender fleshy structures are called . (viii) Muscles bulge due to . (ix) Muscles work in . (x) and of muscle makes the bone move. 3. Fill in the blanks. [Refer to Session 14.3 ] (xi) The body of a fish is . (xii) The skeleton of a fish is covered with . . (xiii) A series of help the fish swim forward. (xiv) The bones of birds are and . (xv) Snakes have a long and several CHAPTER 14. MOVEMENTS IN ANIMALS 65

4. Answer the following questions in one sentence. 66 [Refer to Session 14.2 ] (xvi) What is a ligament? (xvii) What is cartilage? Where is it found? (xviii) What is a skeleton? (xix) In which body joint bones can rotate easily? (xx) Which bone is joined to the skull? CHAPTER 14. MOVEMENTS IN ANIMALS

(xxi) What is present between the vertebrae of the backbone? (xxii) Which bone is present behind the clavicle? (xxiii) Which joint is called pivotal joint? (xxiv) What are shoulder bones? (xxv) Which joint helps us to move our head up–down and side to side? CHAPTER 14. MOVEMENTS IN ANIMALS 67

Short Answer Type Questions 5. Answer the following questions in 3-4 sentences. (i) [(Session 14.2)] What is a skeleton system? Name any two parts of the human skele- ton system. (ii) [(Session 14.2)] What is skull? Write a few lines about it. Long Answer Type Questions 6. Answer the following questions in 6-8 sentences. (i) [(Session 14.1)] How do muscles work? How should muscles work to move a bone? CHAPTER 14. MOVEMENTS IN ANIMALS 68

7. Answer the following questions in 6-8 sentences. (i) [(Session 14.2)] What are ribs? Which organs are present in the rib cage? Write a few points about them. CHAPTER 14. MOVEMENTS IN ANIMALS 69

AS2-Asking questions and making hypothesis Short Answer Type Questions 8. Answer the following questions in 3-4 sentences. (i) [(Session 14.3)] Why do birds fly? Give reason. (ii) [(Session 14.3)] Snails have slow movement? What questions would you ask to know about the slow movement? 9. Answer the following questions in 3-4 sentences. (i) [(Session 14.2)] Why can’t we move our upper jaw? Give reason. CHAPTER 14. MOVEMENTS IN ANIMALS 70

(ii) [(Session 14.2)] What question would ask your teacher to know about hinge joints? AS3-Experimentation and field investigation Very Short Answer Type Questions 10. Answer the following questions in one sentence. [Refer to Session 14.1 ] (i) Based on your observation of human body movement, mention the joint that helps us to move our head upside and down. Long Answer Type Questions 71 11. Answer the following questions in 6-8 sentences. CHAPTER 14. MOVEMENTS IN ANIMALS

(i) [(Session 14.2)] Mohit wants to know about ribs and chest bone. Suggest an activity for him explaining about ribs and rib cage. AS4-Information skills and projects Long Answer Type Questions 12. Answer the following questions in 6-8 sentences. (i) [(Session 14.1)] With the help of internet collect more information on the human skele- tal system. CHAPTER 14. MOVEMENTS IN ANIMALS 72

AS5-Communication through drawing and model making Short Answer Type Questions 13. Answer the following questions in 3-4 sentences. (i) [(Session 14.2)] With the help of diagram explain ball and socket joint. AS6-Appreciation and aesthetic sense, Values 73 Short Answer Type Questions 14. Answer the following questions in 3-4 sentences. CHAPTER 14. MOVEMENTS IN ANIMALS

(i) [(Session 14.3)] Why does a snail move slowly? Give reason. Also state the reason why locomotion is important. Long Answer Type Questions 15. Answer the following questions in 6-8 sentences. (i) [(Session 14.3)] “Your backbone is like a spring”. Do you agree with the given state- ment? Explain. CHAPTER 14. MOVEMENTS IN ANIMALS 74

(ii) [(Session 14.3)] Fish can swim, birds can fly. Appreciate how their structure helps them in this movement. AS7-Application to daily life, concern to bio diversity Short Answer Type Questions 16. Answer the following questions in 3-4 sentences. (i) [(Session 14.1)] How do muscles help in chewing? What role do they play in our body? CHAPTER 14. MOVEMENTS IN ANIMALS 75

Long Answer Type Questions 17. Answer the following questions in 6-8 sentences. (i) [(Session 14.1)] List out the various parts of your body where cartilages are found. Objective Questions AS1-Conceptual Understanding 18. Choose the correct answer. (i) A long structure running down the middle of our back is called (A) Backbone (B) Skeleton (C) Ribs (D) None (ii) joins two bones together. (A) Tendons (B) Ligaments (C) Muscles (D) Cartilages CHAPTER 14. MOVEMENTS IN ANIMALS 76

(iii) Which of the following is not a part of the shoulder? (A) Shoulder bones (B) The clavicle (C)Shoulder blade (D) Ribs (iv) Curiously bent ribs join the and the together to form the rib cage. (A) Back bone, Chest bone (B) Back bone, collar bone (C)Chest bone, shoulder blade (D)Clavicle, Shoulder bone (v) What do you understand by the term ‘vertebrae’? (A) The small bones that make up the backbone. (B) The passage through which the spinal cord runs. (C)A long structure running down the middle of back. (D) None (vi) Given below is a picture of (A) Ribs (B) Pelvic girdle (C) Backbone (D) Skull CHAPTER 14. MOVEMENTS IN ANIMALS 77

(vii) Fixed joints are present in (B) Ribs (A) Shoulder bones (C) Backbone (D) Skull (viii) is a flexible bone. (B) Ligament (A) Cartilage (C) Tendon (D) Fibre (ix) Which body joint is represented by the following picture? (A) Hinge joint (B) Ball and socket joint (C)Neck joint (D)Fixed joint (x) is a type of pivotal joint. (A) Neck joint (B) Skull joint (C)Hinge joint (D)Ball and socket joint CHAPTER 14. MOVEMENTS IN ANIMALS 78

15. LIGHT, SHADOWS AND IMAGES SESSION 1 LIGHT AND TRANSPARENCY 1.1 Mind Map SESSION 1. LIGHT AND TRANSPARENCY 79

1.2 Terminology i. Light –Agent that stimulates sight and makes things visible. ii. Sources of light – Any device serving as a source of illumination. iii. Shadow – A dark area or shape produced by a body coming between rays of light and a surface. iv. Transparent substances – Glass, water, air etc. allow light to pass through them. They are called transparent substances. SESSION 1. LIGHT AND TRANSPARENCY 80

v. Translucent substances – The substances which partially allow light to pass through them are called translucent substances. vi. Opaque substances – The substances like paper, card board, wood, wooden plank, iron sheet etc. do not allow light to pass through them. They are called opaque substances. 1.3 Key Concepts i. We can see object around us because of light present in the surrounding. ii. Any object/ substances which give light is called source of light. iii. Sun, a glowing bulb, a lighted candle, a glow worm etc. are some sources of light. iv. On the basis of the ability of an object to allow the passage of light through them, they are classified as transparent, translucent and opaque objects. v. The substances like paper, card board, wood, wooden plank, iron sheet etc. do not allow light to pass through them. They are called opaque substances. vi. Glass, water, air etc. allow light to pass through them. They are called transparent substances. vii. The substances which partially allow light to pass through them are called translucent substances. Example : Oil paper, ground glass etc. viii. When an obstruction falls in the path of light shadows are formed. 1.4 Conceptual Understanding Q1. Classify the following objects into transparent, translucent and opaque. Cardboard, duster, polythene cover, oily paper, glass, spectacle lens, piece of chalk, ball, table, book, window glass, palm, school bag, mirror, air, water. Which type of materials do you find more in your surrounding? [Refer to TB page 162 Q1] A. Transparent objects: Glass, spectacle lens, air, water. Translucent objects: Polythene cover, oily paper, window glass. Opaque objects: Card board, duster, piece of chalk, table, book, calm, school bag, mirror. We find more opaque objects in our surroundings. SESSION 1. LIGHT AND TRANSPARENCY 81

Q2. We can’t identify the presence of completely transparent objects even in light. Is it correct or not? Support your answer. [Refer to TB page 162 Q3] A. 1) We can identify the presence of completely transparent objects in light. 2) Light transmitted through such objects reaches our vision and so we can identify the objects. 3) The statement given in the question is not correct. 4) However, there are a few transparent objects like air which cannot be seen but only be felt. 1.5 Experimentation and Field Investigation Q1. Hold a glass slab at one end with your hand and stand in sunlight. See the shadows of your hand and glass slab. Explain what you observed. [Refer to TB page 162 Q2] A. i. When I held a glass slab at one end with my hand and stood in sunlight, my hand acted as an opaque object and its shadow was formed. ii. The shadow formed by my hand was visible. iii. But, the shadow of glass slab could not be seen, because the glass slab is a transparent material. iv. Light passed through the glass material and hence shadow was not formed. SESSION 1. LIGHT AND TRANSPARENCY 82

SESSION 2 FORMATION, COLOUR AND SHAPE OF SHADOW 2.1 Mind Map 2.2 Terminology i. Shadow puppetry – Shadow puppetry is one of our traditional recreational activities which uses flat articulated figures (shadow puppets) to create cut–out figures which are held between a source of light and a translucent screen. 2.3 Key Concepts i. Transparent objects do not form shadows. ii. In addition to light and object, we also need a screen to obtain the shadow of an opaque object. iii. Colour of the object cannot be determined by looking at its shadow. SESSION 2. FORMATION, COLOUR AND SHAPE OF SHADOW 83

2.4 Conceptual Understanding Q1. Why can’t we see objects which are behind us? [Refer to TB page 162 Q4] A. i. We cannot see objects which are behind us because light rays incident on that object does not reach our eyes after reflection. ii. To be able to see an object, the light falling on the object should strike our eyes after reflection from the object’s surface. Our eyes can receive the light rays only from the objects which are in front of us. Q2. Why do we get shadows of different shapes for same object? [Refer to TB page 163 Q15] A. (1) We get shadows of different shapes for a same object on changing the position of the object. (2) This is because light rays follow a straight line pa 2.5 Asking Questions and Making Hypothesis Q1. Malati noticed changes in lengths of her shadows during the daytime. She got some doubts about this. What could be those doubts? [Refer to TB page 163 Q17] A. Malati noticed changes in lengths of her shadows during day time. She got some doubts. The doubts could be: (1)Why was my shadow longer early in the morning and why did it become shorter in the noon? (2) What could be the reason behind change in the shape and size of a shadow? (3) Why does the position of the shadow also change? (4) Is there any relation between the intensity of shadow and the brightness of the Sun? SESSION 2. FORMATION, COLOUR AND SHAPE OF SHADOW 84

2.6 Experimentation and Field Investigation Q1. If we focus a coloured light on an opaque object, does the shadow of the object, possess colour or not? Predict and do the experiment to verify your predictions. Coloured light can be obtained by covering torch glass with transparent coloured paper [Refer to TB page 162 Q5] A. i. Take four balls of equal size but different colours. ii. Try to form shadow of each ball as shown using coloured light. iii. If we focus a coloured light on an opaque object, the shadow of the object still does not possess any colour. iv. The shadow formed is always black in colour. Q2. Between an electric bulb and a tube light, which forms sharp shadows of objects? Do experiment to find and give the reason. [Refer to TB page 163 Q6] A. Required materials: Tube light, electric bulb, object, screen. Procedure: 1.Take any desired object and place it under the tube light. Observe the image formed on the screen 2. Similary take the same object and place it under electric bulb. Observe the image formed. 3. Electric bulb forms sharp shadows of objects. SESSION 2. FORMATION, COLOUR AND SHAPE OF SHADOW 85

4. A tube light cannot form sharp shadows of objects. 5. The same thing is proved correct after doing the experiment. Conclusion Bulb light is a point source of light and so it forms sharp shadow of the object. Tube light is an extended source of light and so cannot form sharp shadows of objects. Q3. What is required to get a shadow of an opaque body? [Refer to TB page 163 Q7] A. A source of light, opaque body and screen are required to get a shadow of an opaque body. Q4. Observe the light source and mark the place where the screens should be kept to get the shadows of the objects given below. [Refer to TB page 163 Q18] A. Students are advised to analyse the diagrams and answer the above question accord- ingly. (Students’ activity) 2.7 Communication Through Drawing and Model Making Q1. Draw shadows in your note book for the objects given below assuming that the light source is exactly above these objects. [Refer to TB page 163 Q10] SESSION 2. FORMATION, COLOUR AND SHAPE OF SHADOW 86

A. For each of the objects you can see the shadows, draw them in your notebook. SESSION 2. FORMATION, COLOUR AND SHAPE OF SHADOW 87

SESSION 3 PINHOLE CAMERA AND MAGNIFYING LENS 3.1 Mind Map 3.2 Terminology i. Pinhole camera – A pinhole camera, also known as camera obscura, or “dark cham- ber”, is a simple optical imaging device in the shape of a closed box or chamber. ii. PVC pipe – PVC (polyvinyl chloride) is a common, strong but lightweight plastic used in construction. iii. Magnifying lenses – A magnifying glass is a convex lens that is used to produce a magnified imageof an object. 3.3 Key Concepts i. One of the important property of light is that it travels in straight line which is evident from the shapes of shadows. ii. The image formed by a pinhole camera is inverted. iii. There is difference between images formed through pinhole camera and magnifying lens. SESSION 3. PINHOLE CAMERA AND MAGNIFYING LENS 88

3.4 Conceptual Understanding Q1. Explain what happens if the size of the hole in a pinhole camera is a big as the size of a green gram? Increase the size of the hole in pinhole camera and look at any object with that camera. What do you find? Write reasons for that. [Refer to TB page 163 Q9] A. 1) If the size of the hole in the pinhole camera is as big as the size of a green gram, the sharpness in the image decreases. 2) The image becomes thick and the details of the image are not visible. 3) As the size of the hole increases more light enters and disturbs the formation of the image. 3.5 Experimentation and Field Investigation Q1. How can you explain the straight line motion of the light? [Refer to TB page 163 Q8] A. AIM: To prove that light travels in a straight line. APPARATUS: Pinhole camera, candle EXPERIMENT: Take a lighted candle. Place it on a table and observe it through pinhole camera. We can observe the inverted image of the candle in the pin hole camera. This is because of the straight line motion of the lightrays. Explanation: i. Light which comes from the point at the top of the flame goes straight towards the bottom of the screen. ii. Light which comes from the point at the bottom of the flame goes straight towards the top of the screen. iii. In this way, the light coming in a particular direction from each point of the flame will be able to enter into the pinhole, the light going in other directions is fettered out due to the pinhole. iv. This leads to formation of an inverted image. INFERENCE: The formation of the inverted image of the screen of pinhole camera explains that light travels in a straight line. SESSION 3. PINHOLE CAMERA AND MAGNIFYING LENS 89

SESSION 4 DIFFERENCE BETWEEN IMAGE AND SHADOW 4.1 Mind Map 4.2 Terminology i. Image – An optically formed duplicate, counterpart, or other representative reproduction of an object, ii. Reflection – When light falls on any object, it rebounds back. This is called reflection. 4.3 Key Concepts i. Difference between Image and Shadow is that the shadow does not have colour, but image shows complete object just like the photocopy. ii. Reflection is the phenomenon of rebounding of light when it falls on any object. 4.4 Conceptual Understanding Q1. Where do you find reflection of light in your daily life? Write few examples. [Refer to TB page 163 Q11] A. We find many reflections of light in our daily life. 1) The image of our face in the plane mirror is due to reflection of light. 2) The visibility of objects in and around us is the result of reflection of light. SESSION 4. DIFFERENCE BETWEEN IMAGE AND SHADOW 90

3) The moon is visible to us because it reflects the sun light. Q2. Can we use a plane mirror as a rear view mirror? If not why? [Refer to TB page 163 Q13] A. (1) A rear view mirror helps the driver of a motor vehicle to observe the traffic coming from behind. (2) Then he will either give way or speed up the vehicle as he wishes. (3) So, the rear view mirror should give him a complete picture of the traffic in a dimin- ished image. (4) A spherical mirror should be used as a rear view mirror. (5) On the other hand, a plane mirror forms an image which is of the same size of object. In order to get a complete view of the entire traffic behind we require a large plane mirror which we cannot be fixed in the vehicle. (6) So, a plane mirror cannot be used as a rear view mirror. Q3. A mirror is kept on the wall of your room. Your friend is sitting on a chair in that room. You are not visible to him in the mirror. How do you adjust your place so that you are visible to your friend in the mirror? Explain. [Refer to TB page 163 Q14] A. i. The light ray that emerges from your body is called incident ray. ii. When it falls on the surface of the mirror it is reflected. iii. The incident ray and the reflected ray obey certain rules called “Laws of reflection.” iv. In order to make yourself visible to your friend in the mirror, you have to adjust your position such that the incident ray from you falls on the mirror. v. Then you will be visible to your friend. Q4. What are the differences between a shadow and a image? [Refer to TB page 163 Q16] SESSION 4. DIFFERENCE BETWEEN IMAGE AND SHADOW 91

A. Image Shadow 1. Shadows show only the Image shows the complete outline of the object. object as it is, just like a photograph. 2. Shadows are not Image exhibit the original coloured. colour of the object. 3. Shadows are formed Image is formed when a when an object obstructs light falling on the object is the coming from the source reflected back from a of the light. smooth surface. 4.5 Appreciation and Aesthetic Sense, Values Q1. We would not be able to see any object around us if light does not get reflected. How do you appreciate this property of objects? [Refer to TB page 163 Q12] A. 1) Objects are visible to us only when light falls on it gets reflected and reaches our eye. 2) In darkness or in the absence of light the objects are not visible as light does not reach our eyes from the objects. —— CCE Based Practice Questions —— AS1-Conceptual Understanding Very Short Answer Type Questions 1. Answer the following questions in one sentence. [Refer to Session 15.4 ] (i) What is reflection? SESSION 4. DIFFERENCE BETWEEN IMAGE AND SHADOW 92

(ii) When reflected light is produced? (iii) What precaution should be taken while playing with mirrors? 2. Fill in the blanks. back. [Refer to Session 15.4 ] (iv) When light falls on an object, it is (v) use shadows to tell the time. 3. Answer the following questions in one sentence. [Refer to Session 15.1 ] (vi) When can we see an object? CHAPTER 15. LIGHT, SHADOWS AND IMAGES 93

(vii) What is the time taken for the light to travel from the sun’s surface to earth? (viii) What is a light source? (ix) What do we need to get the shadow of an object? (x) Give an example of an opaque substance. 4. Answer the following questions in one sentence. [Refer to Session 15.2 ] (xi) What do you understand by the term ‘optics’? CHAPTER 15. LIGHT, SHADOWS AND IMAGES 94

(xii) What is a shadow? (xiii) What is the colour of a shadow? 5. Fill in the blanks. . [Refer to Session 15.3 ] (xiv) Light travels in a Short Answer Type Questions 6. Answer the following questions in 3-4 sentences. (i) [(Session 15.1)] What are the primary colours of light? CHAPTER 15. LIGHT, SHADOWS AND IMAGES 95

(ii) [(Session 15.1)] When is an object visible to us? What happens when you hold a plank between an object and youself? 7. Answer the following questions in 3-4 sentences. (i) [(Session 15.2)] What are the requirements for the formation of a shadow? (ii) [(Session 15.2)] What do you understand by ‘speed of light’? Write two lines about it. CHAPTER 15. LIGHT, SHADOWS AND IMAGES 96

8. Answer the following questions in 3-4 sentences. (i) [(Session 15.3)] Differentiate between the images formed by a pinhole camera and a magnifying glass? Long Answer Type Questions 9. Answer the following questions in 6-8 sentences. (i) [(Session 15.4)] Define image and shadow. Write 3 differences between them. CHAPTER 15. LIGHT, SHADOWS AND IMAGES 97

10. Answer the following questions in 6-8 sentences. (i) [(Session 15.1)] Write about transparent and translucent substances giving examples of each. 11. Answer the following questions in 6-8 sentences. (i) [(Session 15.3)] Explain the reason for the inversion of the image of a flame. CHAPTER 15. LIGHT, SHADOWS AND IMAGES 98