and explain why they move in this way.
The picture below shows a radiator heating a room in a house.
gcsescience.com 8 gcsescience.com
Heat - Convection (continued from the previous page).
You may be asked to draw the
direction of convection
currents
and explain why they move in this
way.
The picture below shows a radiator
heating a room in a
house.
The hot
radiator transfers heat to
the nearby air
when air molecules collide with the radiator surface.
The air is also heated by infra-red radiation.
The hot air near to the
radiator expands and increases
in volume.
Hot air
expands because the particles
move
further apart as they get hotter (see the
structure
of a gas).
This makes the density of
the hot air decrease
and it starts
to rise
upwards. The colder air above it gets pushed along
to the right and then circulates as shown by the
arrows.
The arrows show how the convection currents
move.
As the hot air moves around
the room,
it loses its
heat by collision
with the walls, ceiling and the objects
in the room. Finally the colder air circulates near to
the radiator where it is heated and the whole process
repeats
itself. The efficiency of convection can be
improved
by placing shiny metal
foil behind the
radiator.
Links
Energy
Transfer
Revision Questions
gcsescience.com Physics Quiz Index Heat Quiz gcsescience.com
Home GCSE Chemistry GCSE Physics
Copyright © 2015 gcsescience.com. All Rights Reserved.