ICSE Class 8 Physics, Unit 6: Heat Transfer

What this unit aims at

In both boiling and evaporation, matter changes from liquid to gas. But the two processes are quite different. When temperature of a matter increases, the particles of the matter gain energy and move with greater speed. In evaporation, the particles at the surface escape and form gas. Other particles, inside the liquid, do not have enough energy. So the process of evaporation occurs at the surface. It happens at all temperatures. In boiling, all particles of the liquid are at the same temperature and are involved in the process. It happens in the whole volume of the liquid and it happens at a fixed temperature, particular to a liquid. But before change of states takes place due to supply of heat, there is another effect which is commonly observed. That is the expansion of matter. Matters in all form, except some exceptions, expand on heating. In solids, the effect is less, in liquids mor

Your child should be able to

• compare and contrast Boiling and Evaporation
• describe thermal expansion of matter
• describe, linear, area(superficial) and volume expansion
• compare expansivity in Solids, Liquids and Gases
• construct models based on scientific process
• observe and cite multiple physical phenomena from one experiment

Key concepts in this unit

• Difference between Boiling and Evaporation.
• Thermal Expansion:
• Linear Expansion Volume Expansion Superficial Expansion Compare expansivity in Solids, Liquids and Gases.
• Examples and real- world applications.