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www.GOALias.blogspot.comFig. 4.8 Conduction of heat by differentmaterialsheat is transferred by the process ofconduction.Do all substances conduct heateasily? You must have observed thatthe metallic pan for cooking has a plasticor wooden handle. Can you lift a hotpan by holding it from the handlewithout getting hurt?Activity 4.7Heat water in a small pan or a beaker.Collect some articles such as a steelspoon, plastic scale, pencil and divider.Dip one end of each of these articles inhot water (Fig. 4.8). Wait for a fewTable 4.3ArticleMaterial withwhich the articleis made ofSteel spoon Metal Yesminutes. Touch the other end. Enteryour observation in Table 4.3.The materials which allow heat topass through them easily areconductors of heat. For examples,aluminum, iron and copper. Thematerials which do not allow heat topass through them easily are poorconductors of heat such as plastic andwood. Poor conductors are known asinsulators.The water and air are poorconductors of heat. Then, how does theheat transfer take place in thesesubstances? Let us find out.Activity 4.8Take a round bottom flask (if flask isnot available, a beaker can be used). Fillit two-thirds with water. Place it on atripod, or make some arrangement toplace the flask in such a way that youcan heat it by placing a candle below it.Wait till the water in the flask isstill. Place a crystal of potassiumpermanganate at the bottom of the flaskgently using a straw. Now, heat the waterby placing the candle just below thecrystal.Write your observation in yournotebook and also draw a picture ofwhat you observe (Fig. 4.9).When water is heated,the water near the flame getshot. Hot water rises up.The cold water from thesides moves down towardsthe source of heat. Thiswater also gets hot and risesDoes the otherend get hotYes/NoHEAT4141