Transcript Points to be noted

The Earth is divided into
(1)crust (2)mantle (3)core.
The 3 layers have
different thickness
and characteristics.
Temperature and pressure increases
with depth.
Therefore,
The crust is the coldest.
The core is the hottest.
Points to be noted :
The crust is mainly composed of granite.
It forms the distinct landforms and the continents.
Points to be noted :
The mantle is divided into 2 layers : Upper and Lower mantle.
The upper mantle is further divided into 2 layers.
The top layer is the lithosphere.
The bottom layer is the asthenosphere.
The lithosphere consists of hard rocks.
The asthenosphere consists of partially melted rock.
The crust and the lithosphere overlies this layer and slide on this layer.
Very little things is known about the lower mantle.
Points to be noted :
The core is divided into 2 layers : the Outer and Inner core.
The outer core is liquid and is composed of molten metal.
The inner core is solid because the pressure is very great.
Since the pressure is very great, all the materials inside this layer
is highly compressed and this prevents them from melting despite
of the high temperature.
The inner core is mainly composed of iron and nickel.
What is geothermal power ?
“Geothermal” is Greek word.
geo  earth
thermal  heat
Geothermal energy is heat from within
the earth.
Application :
Steam and hot water produced inside
the earth can be used for
1. heating buildings
or
2. generate electricity.
Group discussion :
How can we make use of geothermal
power to generate electricity ?
Water pipes can be constructed deep
underground.
The water is heated up to form steam
which moves the turbine.
The turbine then drives the generator to
produce electricity.
Group discussion :
Discuss the advantages and
disadvantages of using geothermal
power.
Advantages :
Geothermal energy is a renewable
energy.
(i.e. never exhaused)
It causes no pollution.
No fuels is required
so it is insusceptible to fluctuations in
fuel cost.
Disadvantages :
It needs high technology.
(Example : Deep underground water
pipes have to be built.)
Construction cost is expensive.
Hot water from geothermal sources
may contain trace amounts of
dangerous elements such as mercury,
arsenic, and antimony which, if
disposed of into rivers, can render
their water unsafe to drink.