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)
