Ivar Utial Colour Edition +10 NEW A revolutionary approach to learning basic scientific facts by performing experiments with the help of Tutorial CD Rom Publishers Pustak Mahal, Delhi © Pustak Mahal, Delhi ISBN 978-81-223-0950-8 Edition : 2008 101 Science Experiment's Ivar Utial P U S T O K ^ f f i A i : Delhi • Bangalore • Mumbai • Patna • Hyderabad Preface I n this Age of Knowledge, a person who is indifferent to science and lacks a scientific temper will get left far behind in the race. Not only this, his casual attitude towards this vital might someday endanger his own life and those of others, for all around us are objects that reflect the bounty of science, but which can be very dangerous if mishandled. Imagine what would happen if the benefits of science are taken away from your day-to-day life. You would be transported in time to the Dark Ages, a time when human beings wallowed in superstition, ignorance, disease and misery. You wouldn't like to lead such a miserable life, would you? Science is a very useful and fascinating subject, but its most amazing aspect is that despite its being very close to us "in our day-to-day lives, many of us choose to keep ourselves ignorant about even its most basic principles. Given its crucial importance in understanding our technical world and our function within it, a closer study of science - and acquaintance with its basic principles and priorities - is unavoidable. Thus, what is required of you is that should get properly acquainted with it, and make sincere efforts to understand it. On my part, I will do my best to write books for you that are interesting, attractive and instructive, so that whatever you absorb will stay with you throughout your life, and become a foundation for further growth. This book teaches you how to do small experiments all by yourself, so that you can easily understand the basic principles involved. I have taken care to select only those experiments where the required apparatus or materials are easily available, having received many letters on this point in respect of the previous edition. While it was impossible for me to reply to all of them individually, I have responded in the desired manner by incorporating the suggestions. I again invite your views and suggestions for improving the book further in the next edition. By being a good citizen of the country, may you progress successfully on the path of life and achieve distinction of worldwide renown for the country in the field of science. My sincere good wishes are always with you! uUlpJ Ivar Utial Contents Is a visibly empty vessel really empty? 1 Does air occupy space? 2 Let us see, how much is the stamina of your lungs? 3 Importance of atmospheric air pressure 4 Making a barometer 5 What is the effect of heat on air? 6 Air expands when heated 7 What happens when air is heated? 8 Does the air contract, as it cools, in the same way, as it expands when heated? 9 Has air any weight? 10 How does wind blow? 11 Why ice floats on water? 12 What is evaporation? 13 Reason to feel cold after bathing 14 What is the effect of strong wind and heat on evaporation? 15 What is condensation? 16 Natural process for evaporation and condensation 17 What is coalescing? 18 Water acts like a thin film 19 What is water level? 20 What is (total) reflection? 21 Translucence or opaqueness? 22 Speed and the 'cage of death'? 23 What is inertia? 24 Practical inertia 25 Constructing a water dam at home 26 Detecting starch and fat in food 27 Law of gravity 28 Is it possible that you hold a test tube in your hand in which water is being boiled? 29 What is the effect of heat on the volume of water? 30 Does the weight of water undergo any change when heated? 31 In winter, we are protected from cold when we wear woollen clothes. Why is it so? 32 Do the metals expand on heating? 33 Can solid objects transmit heat? 34 Is copper a good conductor of heat? 35 How can acids and bases be identified? 36 How can it be known that the air we exhale contains carbon dioxide gas? 37 Does carbon dioxide really help in putting out fire? 38 What happens when a lighted candle is kept inside a closed vessel? 39 Is there any easier method to prove that carbon dioxide is heavier than air? 40 Effect of rusting 41 Speciality of a electric bulb 42 How are pulleys useful? 43 What are jet aircrafts and what is the principle they operate on? 44 How does an aircraft fly? 45 What is combustion? 46 What happens when elements are burned? 47 How does a camera clicks photos? 48 Our eyes see every object upside down—this statement is as amusing as it is true. But how? 49 Is it true that the distance between the image and the mirror is equal to the distance between the object and the mirror? 50 Reflection changes with distance 51 What is a telescope? 52 What is refraction? 53 Properties of light 54 The sunlight is a combination of seven colours—how far is this statement true? 55 Have you ever seen a circular disc which appears colourful if stationary but totally white when rotating? 56 How do we see different colours? 57 Is there any relation between the colours and reflection of light? 58 Why do we like to wear clothes of light shade in summer? 59 How do the pictures on the cinema screen appear to be dancing, jumping and moving? 60 Can the properties of a magnet be produced in an ordinary needle? 61 Making a magnetic compass 62 What all does a magnet attract? 63 The strength of a magnet is not at all related to its size—is it a true statement? 64 Controlling flowing electric current 65 Like all other types of magnets, does an electromagnet too have two poles? 66 To prove by a simple experiment that unlike electric charges attract each other 67 Is there any such method with the help of which electricity can be generated anywhere, at anytime, without much ado about it? 68 A game of puffed rice grains suspended by a silk thread 69 Is it possible to safely store static electricity for future use? 70 What is a two-way switch? 71 What is a fuse? 72 How is a telegram sent? 73 Making a generator at home 74 What is sound and how is it produced? 75 Does sound necessarily need a medium to reach you? 76 Hearing the heart-beat 77 Can it be proved by an experiment that the trunk of a tree always grows upwards and the root downwards? 78 How would you find out whether the growth of all the parts of the root is uniform or the growth of a particular part is more than the other parts? 79 How does the water absorbed by the roots from the surrounding soil reach the other parts of the plant? 80 The water drawn by the roots from the earth gives life to the plants and trees, but then, what happens to the water? 81 What is a wind vane? 82 Making an anemometer 83 How to measure direction of wind? 84 How to measure humidity in air? 85 How to measure gravity in liquids? 86 How to measure rainfall? 87 What are turbines and how do they rotate with the help of water? 88 What is photometer? 89 Making a microscope at home? 90 Can you measure the height of a building or a tree, etc. without climbing on it? 91 Cleaning the silver articles 92 What are stalactites and stalagmites and how are they formed? 93 How do fingerprints help in detecting criminals? 94 How to trace footprints? 95 How is it possible to measure the distance between the earth and various heavenly bodies so accurately while sitting on earth? Do you know? 96 How can we measure the temperature of the moon and other heavenly bodies? 97 The astronomers have their own method of recording the temperature of the celestial bodies? What is it actually? 98 Is it possible that your tongue may at times deceive you in recognising a particular taste? 99 Is it ever possible that the sensitivity of your skin may deceive you too? 100 When your own eyes deceive you! 101 + 10 new experiments in CD • science e x p e r m i e h t s • f t Is a visibly empty vessel really empty? T ake an empty glass bottle and remove its cap. Hold it upside down and immerse it into a vessel filled with water. Now watch the activity carefully. Water enters the bottle and rises up only upto a certain point. Now immerse the bottle deeper in the water. But, what is this? The level of water inside the bottle remains unchanged, while the level of water outside the bottle rises up gradually. Can you understand the reason? It is quite apparent from this experiment that there is definitely something inside the bottle which is preventing the water from entering it. What else can this invisible thing be except the air itself? Now do one thing. Tilt the bottle a little to one side. Oh! What's this? The bubbles coming out of the mouth of the bottle are rushing noisily to the surface and meeting their end by bursting out there. These bubbles are of air only. The air trapped inside the bottle gets an opportunity to escape when the bottle is tilted to one side, causing the water to fill the vacuum thus created by the exit of air. • SCIENCE GXPGRimEriTS • Does air occupy space? Keep a funnel on the mouth of a bottle and fill half of it with water. Now, while filling the remaining half of the bottle, raise the funnel, a little higher. Does the speed with which the water fills the bottle remain unchanged in both the cases? W hen you keep the funnel on the mouth of the bottle and pour in water through the funnel, the speed with which the water enters the bottle is very slow. But the moment the funnel is * raised a little higher, the water starts rushing in at a great speed. Do you know why this happens so? It is quite obvious. When water starts filling the bottle through the funnel, it exerts pressure on the air trapped inside the bottle, and as such, the air does not get an easy escape. Though the funnel is placed on the bottle in such a way that it covers the mouth of the bottle almost fully, yet, since the covering is not airtight, the air inside manages to get a little opening to escape. Hence, the speed with which the air inside the bottle goes out remains equal to the speed with which the water fills the bottle. Thus, when the funnel is raised a little higher, the air inside the bottle gets a free outlet to escape. It is through this outlet that water wades its way through the air in the bottle by pushing it out with great speed, quite unobtrusively. SCICflCC E X P E R I M E N T S D Let us see, how much is the stamina of your lungs? T his experiment will not only determine the power of your lungs, but its regular practice will prove to be a good exercise to tone up your entire respiratory system. Take a big shallow bowl and fill it with water to about 5 to 7 cm in height. Then take an open-mouthed big bottle or ajar, fill it fully with water and tighten its cover quite firmly. Now, hold the bottle upside down, immerse it in the water in the bowl and remove its cover. Mark the level of water inside the bottle and tilt the bottle to one side. You will need a hollow rubber tube whose one end should be inserted inside the inverted bottle, leaving the other end hanging freely outside the bowl. Now, be ready yourself to measure the power of your lungs. Inhale as deeply as you can and then blow the air forcefully inside the free end of the tube by your mouth. Observe simultaneously the volume of water you can displace and fill in the air instead. Mark this level of water also. The difference between the two marks shall determine the capacity of your lungs. But be careful that while blowing the air inside the tube, you do not either break your breath or inhale. If by its regular practice for a few days you find the difference between the two marks increasing, deem it that you are getting the due benefit, from this exercise. sciEnce E H P E R i m e m s Importance of atmospheric air pressure The atmospheric air pressure is extremely beneficial for us, for its absence would have made it impossible for us to drink anything through the straw. T ake some water or any other drink of your choice in a glass tumbler. Put two straws into it. Now hold one of the free upper ends of the straw by your mouth and suck in air from it. This suction will mean that you are drawing out part of the air held inside the straw. The air outside the straw starts asserting the moment part of the air from inside the straw reaches your mouth. It starts putting pressure on the drink to fill in the vacuum created by the air sucked in by you from inside the straw pipe. This process of sucking in the air and filling in the vacuum thus created by the drink continues till the drink remains in the tumbler. The second straw lying in the tumbler remains unfilled by the drink as the conditions of varying air pressure do not apply on it. • science c x p c R i m e m s • a Making a barometer The device used for measuring the atmospheric pressure is called a barometer. Why don't you make one yourself and see how it works and measures the atmospheric pressure? T ake a wide-mouthed bottle and stretch the neck of a balloon clamping it on its mouth. Bind it also with the help of a rubber band in such a way that the balloon is fully stretched on the mouth of the bottle. Now, take a drinking straw and attach one end of it on the centre of the stretched balloon with 'Quick-fix' (an adhesive agent). Then, continue to hold the straw in the same position till the 'Quick-fix' gets dry. After accomplishing this, you have to do only one more job — to set a white strip of cardboard by the side of the bottle in such a way that it remains standing upright, just behind the free end of the straw. BJ— Graduate this . cardboard strip with the marks indicating 'high and low' degree signs. Now, your barometer is ready. As you know, when the atmospheric pressure is high, it will exert a similar pressure in all the directions. So much so, that the pressure on all the sides of the bottle will be equal, causing slight deflation in the balloon towards the inside of the bottle. This in turn will put pressure on the attached end of the straw and its other end will rise higher to indicate the increase in the pressure. On the contrary, if the atmospheric pressure decreases, the balloon will not be deflated. But if the pressure becomes so low as to be even less than the air pressure inside the bottle, it will inflate the balloon and the free end of the straw, quite obviously, will indicate the decrease in the atmospheric pressure. n scicncc CHPCRimenTS What is the effect of heat on air? T o conduct this experiment, you will need a flask type bottle with cork or rubber stopper and a slender tube. Drill a hole in the cork and insert the tube through the hole. Then fix the cork along with the tube tightly on the mouth of the bottle. Lac or grease can be used to make the joints air-tight. Keep one thing in your mind that the thinner the glass of the bottle, the better will be the success of the experiment. Now, turn the bottle upside down and hold it in such a way that the other end of the tube remains immersed in the water kept in some vessel. Now, ask one of your friends or a member of your family to rub his hands and hold the bottle. You will see some bubbles rushing from the mouth of the tube to the surface of the water and bursting out there. Now, do one thing more! Take a piece of cloth spread out in the sun and fold it to wrap it around the bottle. See, what happens? What do you say? Some more bubbles come from the mouth of the tube and appear on the water surface. Don't they? It is so because the heat of the hands or the warmth piece of the cloth permeates through the air inside the bottle to cause it to expand. That part of the expanded air which cannot be contained in the bottle comes out through the tube and can be seen in the form of bubbles. • SCICI1CG E X P E R i m E H T S Air expands when heated F or this experiment, you will flask—a special type of v e s s e l — w h i c h you can easily procure from any shop dealing in laboratory equipments. You are already seeing its shape in the adjoining illustration. In the previous experiment also, you will do well if you use a flask instead of an ordinary bottle. Fix a balloon on the mouth of the flask and then heat the flask, slowly. Now tell me, what will happen? If you have carefully followed the earlier experiments, you can easily tell without any hesitation that the balloon will inflate as it fills with air. But from where the air which fills the balloon come? The answer is very simple, isn't it? It always seems so when you have comprehended the phenomenon fully. It must be quite clear from the earlier experiments that air expands when heated. The same is the reason here as well. When the flask is heated, the air inside it expands and as it needs more room in this condition, it goes out of the flask and inflates the balloon. -Ill