Before this section, you have read about how
white light can splitted into its component colours and why do you see the various colours
of opaque objects. In this section, we will probe into the interaction of matter and
light. What is an opaque, transparent and translucent object ?
When light strikes ...
When light strikes any form of
matter, it can be either transmitted, absorbed or reflected. The aspect
on how it is absorbed has already been covered. Go for Colours of
Objects if you have not done so.
Transparent Objects
They are those that allow
light to pass through readily. These kind of objects have absolute clarity. You can see
right through them ! Thus, a cear image can often be witnessed from the other side.
However, with the exception of a vacuum nothing is ever seen-through completely. Usually
when light passes through such objects, some energy will naturally be absorbed by them.
Thus, the thicker the object the more energy it will absorb. That accounts for why thinner
objects seem to be clearer than thicker objects when light passes through them
respectively. The water, air and glass are all transparent objects.
Translucent Objects
These kinds of objects scatter
or disperse light when light falls on them. They are said to transmit light in the absence
of details. You can only see a blur image when you peek through these objects.
Nevertheless, just like transparent objects their clarity is also dependant on thickness.
Take for instance a piece of paper. Hold it up before a lamp. Some fibres of the paper
will scatter and absorb the light and some will still penetrate through the paper. That is
why when more sheets of paper are gradually added, the clarity of the increasing stack of
paper decrease proportionally. In the case of translucency, temperature also sometimes
plays a vital factor. Most fats and waxes somehow scatter light when they are in their
liquid states. Once again, this explains why they become clearer when they are in liquid
state. Lastly, Frosted glass and waxed paper are examples of translucent objects.
Opaque Objects
Simply to put it, these
objects do not allow light to pass through. Instead, they absorb some of the light that is
cast on them. All the light you see is thus refected by the object's surface. Wood, paper
and many more are examples of such objects.
