Unit 6: Light and Sound





What is Energy


Energy is defined as the ability to do work. Light, sound, electricity and heat are some forms of energy. Most of the Earth's energy comes from the Sun.


Transforming Energy


Energy can be transformed from one form to another. In a lamp, electrical energy transforms into light and heat.


Online Activities












Different Types of Energy



Solar Energy


Solar energy is one of the Earth's most important renewable energy sources. We get solar energy from the rays of the Sun. Solar energy can be transformed into heat and electricity. 

Thermal Energy


Thermal energy is the internal energy that comes from the motion of small particles in every substance. The faster the particles, the warmer it gets. Geothermal energy is a good example of this.

Chemical Energy


Chemical energy is the energy stored in the bonds of atoms and molecules. Chemical energy is caused by chemical reactions. Natural gas is a good example of this.

Mechanical Energy


Mechanical energy is produced by objects in motion. Wind power and hydropower are good examples of this.

Electrical Energy


Electrical energy is the energy electrons in motion produce.




Light is a type of energy that can be seen by the human eye. It is a type of electromagnetic radiation. Other types of elctromagnetic radiation are radio waves, x-rays and microwaves.


White Light


When light passes through a prism, it is broken into separate colours. This rainbow of colours is called a spectrum. White light is what the human eyes sees when all the colours of the spectrum are combined.


Online Activities






The Properties of Light




When light hits some surfaces, it reflects. If it hits a smooth and flat surface, all the rays reflect in the same direction. If a surface is not smooth, light relects in different directions.





Refraction occurs when light moves through materials of various densities. When this happens, the rays of light curve.






Sound is a form of energy. It is produced when matter vibrates. Sound is a vibration that travels in waves in all directions. Sound waves can pass through gases, liquids and solids.


Sound can be loud or quiet.


If the vibrations of sound are fast, the sound is high like a violin. If the vibrations are slow, the sound is low like a cello.


Noises are unpleasant sounds.



The Characteristics of Sound




Pitch tells us if a sound is high or low.




Duration tells us if a sound is short or long.




Intensity tells us if a sound is loud or quiet.




Timbre allows us to tell the difference between sounds, like the difference between a classical guitar and an electrical guitar.