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Transfer ofTransfer of
heat :heat :
Transfer of heatof heat
• A form of energy.
• Travels from a hotter region to a colder region until
both regions are of the same temperature.
• Transferred from a warmer to a colder region in three
What is convection?
• The transfer of heat by the circulation of currents
from one region to another in a fluid (liquid or a
• Convection above a hot surface occurs because
hot air expands, becomes less dense, and rises.
• Hot water is likewise less dense than cold water
and rises, causing convection currents which
Examples of convection:
Heated water in the pot expands and becomes
The warmer water will then rises while the cooler
and denser water near the surface descends.
Convection currents are formed.
Atmospheric convection is a very important
part of Earth’s weather.
In atmospheric convection,
Warm air moves upwards.
Cool air falls downwards.
When a fire was lit up at the bottom,
Hot air expands, becomes less dense, and
Cooler air from outside the coal mines enter the
mines to take the place of the leaving air.
Mines were thus ventilated with continuous supply
Natural and forced convectionNatural and forced convection
• It is caused by buoyancy forces due to density
differences caused by temperature variations in
The buoyancy forces caused density
differences in the air inside the room
thus, convection occurs.
• In forced convection, fluid is circulated by a plump or
In human circulatory system, a heart is
needed to pump the blood to other parts of
• Appliances such as
refrigerators make use
of convection to heat
up or cool down liquids
or gases rapidly.
Applications of convection
What are the three different ways
of Heat Transfer?
Convection , Conduction &
What is convection ?
It is the transfer of heat by
the circulation of currents
from one region to another in a
fluid (liquid or a gas).
What is the function of
Convection current transports energy.
What are the two types of
They are natural convection and forced