Lesson
8 Energy, heat, sound and light
Energy can experience physical and chemical
energy, energy produce a change in matter.
Energy hasn´t got mass or volume. It
can be contained (for example in batteries). It can´t be destroyed and can
be perceived in different ways:
-
Kinetic Energy:
Everything that moves contain kinetic energy.
-
Chemical Energy:
Combustibles or objects that
can explode contain chemical energy.
-
Thermal Energy:
Heat.
-
Luminous energy:
It´s the light produced by objects,
for example the sun.
-
Electrical
energy: like a lightning in a storm.
-
Magnetic energy:
Produced by magnetism
We can find two kinds of energy sources:
-
Renewable: they doesn´t run out when we use them.
-
Non- renewable: They can´t be replaced when we use them.
Heat contains thermal energy and we can
measure it. It´s called temperature. We can transfer heat by contact (if
we touch the object) or at a distance (for example the sun).
The heat can vary the temperature in
objects and produce physical changes.
Sound has got kinetic energy. It originates from
something vibrating. It has an effect on matter because it transfer kinetic
energy.
Light can be natural or artificial. It’s a
form of energy. Light travels in a straight line, in all directions and it
travels faster than other type of energy. There are transparent objects (they
allow light to travel through them), translucent objects (allow some light to
pass through them) and opaque object (don´t allow light to travel through
them).
There are three phenomenons related to
light:
-
Dispersion: White
light separates into colours.
-
Reflection: The
rays of light bounce in different surfaces and are called reflected rays.
-
Refraction and
lenses: The bending of light in objects is called refraction. There are two
types of lenses, convex (that make objects look bigger) and concave (the
objects seem smaller)
