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Chpt 17-Effects of Heat and Its transmission - Coggle Diagram
Chpt 17-Effects of Heat and Its transmission
Effects of expansion and contraction
Expansion and contraction may cause damage to structures that are constantly exposed to the environment
For e.g.(telephone wires and electricity cables,tiled and concrete pavements,laboratory glassware and water pipes)
Uses of expansion:
Opening a jar,Rivets,Bimetallic strips
Uses of bimetallic strips
Thermostat,Bimetallic thermometer and Oven
Movement of Heat
Heat occurs through conduction,convection and radiation
Conduction is the process of heat transfer through a medium or material without any movement of the medium or materal
Use of heat conductors:Good conductors are used whenever heat has to be quickly transferred from one place to another
Use of heat insulators:Bad conductors are used to reduce the amount of heat transfer
Convection is the transfer of heat from one place to another by the movement of fluids(liquids and gasses)
Convection in liquids:As the water is heated it expands and becomes less dense.This causes the rice grains to rise towards the surface of water.The cooler water at the surface is denser and sinks
Examples:Car radiator,land and sea breezes
Radiation is the transfer of heat,in the form of waves from one place to another.It does not require a medium for transmission
The darker ad rougher the surface of the material the higher the rate of radiation or absorption
What effects how fast a certain material radiates
Nature of the body and total surface area of the body
A vacuum flask stays hot because the vacuum flask is designed to reduce heat loss from the liquid by conduction,convection and radiation.The different parts of the flask work together to keep the liquid hot