Description
- Overview:
- OBJECTIVES:At the end of the topic students will be able to:1) Students will be able to understand the effects of heat on the states of matter.2) Students will gain in depth understanding of the concept of thermal expansion and contraction of solids.3) Students will apply the concept of thermal expansion and contraction of solids in their day-to-day life.Standard:7th Standard and aboveContent Analysis:New Terms i) Change of state of a substance ii) Expansion and contraction of solidsDefinition:The changing of solids into a liquid and a liquid into a gas on heating is called a change of state of a substance.Concept:For a substance to undergo a change of state, heat must either be given to it or taken away from it.Examples:1) When we place the ice on a table it gets converted into a liquid.2) On heating water, it gets converted into the vapour that is the gaseous form.3) On cooling the hot water it gets converted into the liquid form. When we place a lid on the top of the hot water, water droplets are formed on the surface of the lid that is condensation takes place.4) When we put water in a refrigerator it becomes ice after sometime.Expansion and contraction of solids:On heating most solids expand that is their length or volume increase. While on cooling solids contract.Examples:1) If the tin lid of a bottle is struck on too tightly, we often dip it in warm water to help open the bottle.2) If two metal bowls have got struck one inside the other, we place them in hot water. This helps to separate the two bowls easily.Experiment:When the metal wire is heated it expands. That is, its length increases. As a result it pushes the pointer. If we stop heating the wire it cools slowly and contracts and the pointer goes back to its original position. Thus we see that solids expand when heated and contract when cooled.
- Subject:
- Applied Science
- Level:
- Middle School
- Grades:
- Grade 7
- Material Type:
- Lesson Plan
- Author:
- Kajal Rk Gupta
- Date Added:
- 09/14/2016
- License:
- Creative Commons Attribution Non-Commercial No Derivatives
- Language:
- English
- Media Format:
- Downloadable docs
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Nice information.........