- An object is intuitively assumed to exist and to be responsible for a unified experience, consisting of visual and other sensations and perceptions.
- Every object, material, medium or substance that we can see is made of matter of one kind or another. The key differentiating factor is the elements and molecules they are constructed from.
- You will have come across the elements that make up the periodic table.
- A close look at molecules reveals that they are made up of atoms composed of electrons surrounding a nucleus of protons and electrons.
- Light illuminates objects. In a nutshell, different elements and molecules react to light in different ways because of their atomic structure and the particular way they combine to form mixtures or compounds.
- In the case of an opaque object, it is the molecules that form its surface that determine what happens when light strikes it. Translucent and transparent objects behave differently because light can travel through them.
- Another factor that needs to be taken into account when light strikes an object is surface finish. A smooth and polished surface behaves differently from one that is rough, textured or covered in ripples.
