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a ee., : Keywords, , , , 1, Amber : It is a kind of resin, when rubbed with fur,, , ots light objects such as hair., , - Static electricity : The electrical charge generated by, , subbing is called static electricity, because these charges do not, ove. i:, , ‘ 3. Electric current electricity : When charges move,, , they constitute an electric current,, , 4, Charging : If a charge is produced on an object, the, process is called charging., , 5. Discharged : The object which lost charge, is called, discharged object., , 6. Earthing : The process of transfer of charge from a, charged object to the earth is known as earthing., , 8 1), , 7. Lightning : When negative charges from the clouds, and positive charges on the ground meet, huge amount of, ‘nergy is produced as bright light and sound. It is called, lightning., ke 8. Lightning rod : It is a device used to secure tall building, , m the effect of lightning., , 9. Cyclone ; Sometime there is a formation of very low, a ure System with very high speed winds revolving around., , 8 called a cyclone., , 10, Thunderstorm : The swift movement of falling water, Te along with the rising air create lightning and sound., , ‘“alled thunderstorm. :, , Seng eatthquake : An earthquake is a sudden shaking or, "4. U8 Of the earth., , o Seismic waves : The waves on earth produced by the, os Known as seismic waves., , Richter scale : The power of an earthquake is expressed, of magnitudes on a scale called Richter scale., , , , , , , , ° 247
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Exercises, , Select the correct option in Questions 1 and 2., , Q, 1. Which of the following, by friction?, , (a) A plastic scale, , (b) A copper rod, , (c) An inflated balloon, , , , cannot be charged easily, , (d) A woollen cloth., , Ans. (b) A copper rod, , Q. 2. When a glass rod is rubbed with a piece of silk, cloth the rod, , (a) and the cloth both acquire positive charge., , (b) becomes positively charged while the cloth has, a negative charge., , (e) and the cloth both acquire negative charge., , (d) becomes negatively charged while the cloth has, a positive charge., , Ans. (6) becomes positively charged while the cloth has, , Q. 3. Write T against true and F against false in the, following statements., , (a) Like charges attract each other (T/E), (6) A charged glass rod attract a charged plastic, Straw (T/F), , (c) Lightning conductor cannot protect a building, om lightning (T/E), , (d) Earthquakes can be predicted in advaoce (T/F), Ans. (a) F (6) 'T (c) F (d) F, , i, ne 4. Sometime, a crackling sound is heard while, ng off sweater during winters. Explain., Ans. Th, Weater jg, q ‘arge,, , © cracking sound is heard because when the, rubbed while taking it off, it a quires a small
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5, Wxplain why 4 charged body loses ils charge ip, we dee it with our hand,, , ; uctor of electricity, When we |, Ans, Our body ie a cond Beier gd body lone, Ouch, harged body with our hand, the charge ¥ love charg, ha ‘, , ¢, ‘ hrough our body,, , i t, , to the ea th gd, , sale on which the destructive Cnerpy, , Q. G6, Name the se ale |, , of an earthquake is measured, An earthquake Measures, , § on this scale. Would it be recorded by a seismopraph?, ,, , Is it likely to cause much damage ?, , Ans. The destructive energy of an earthquake {8 Measured, on a scale called Richter scale,, , An carthquake measure 8 on this seale will he recorded, by a seismograph, However, it is nol likely to cause much, damage., , Q. 7. Suggest three measures to protect ourselves, from lightning., , Ans. (i) Hearing thunder, we should rush to a safer place, like house or building., , (ti) If no proper shelter ig available and we are in a open, field then he/she should stay away {rom trees, poles and other, metal objects. We should not lie on the ground, instead, squal, low on the ground i.e, a position where hands are put on, knees with head between the hands,, , _ (iti) If we are inside the house, telephone cords, electrical, wires and metal pipes should be avoided. Bathing should also, be avoided to avoid contact with running water,, , Q. 8. Explain why a charged balloon is repelled by, another charged balloon whereas an uncharged balloon, 1s attracted by another charged balloon ?, , Ans. A charged balloon is re, balloon because both have the s, similar charges repel each other,, , But a charged b, lose its own charge, , i" Q, 9. Deserib, instrument which, , pelled by another charged, ame charge, And we know, , alloon attracts an uncharged balloon and, lo the other balloon,, , e with the help of a diagram 8”, an be used to detect a charged body:, , se
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Fig. 15.1 A simple electroscope, , A device that is used to test whether on object is carrying, charge or not is known as electroscope., , Q, 10. List three states in India where earthquakes, are more likely to strike., , Ans. The sates that fall in seismic zones are more, tarthquake-prone. Jammu and Kashmir, Himachal Pradesh, and Gujarat are a few such states., , Q. 11. Suppose you are outside your home and an, tarthquake strikes. What precaution would you take, to protect yourself ?, , Ans. Following precautions could be taken to protect, ourselves in a earthquake, if we are outside home :, , _ (i) First I will find a clear spot, away from buildings, trees, ind overhead power lines and will drop to the ground., : Tf am in a car or a bus, I will not come out. eae, a told driver be told to drive slowly to a clear spot and w!, , “ome out till the tremors stop., , ‘ el? The weather department has predicted ee _, iderstorm is likely to occur on a Se il on, Se you have to go out on that day. Would y, , * a2 umbrella ? Explain., , ause the, Ss. N, umbrella. Becaust, ee I would not carry a Belgien tet: lighting.
