Light, Shadows And Reflections

If we are able to see clearly through an object, it is said to be transparent. Whereas there are some objects through which we can see but not clearly. Such objects are known as translucent objects.
Transparent objects allows light to pass through them completely whereas translucent objects doesn’t allow light to pass through them completely.

Pinhole camera can be made with simple material like cardboard, tracing paper etc. It can be used to image the sun and brightly lit objects.

Light travels in a straight line and when opaque object obstructs it, shadow is formed.

When any surface reflects light without absorbing it, it is known as reflection.

Transparent-glass and water.
Opaque-wood and plastic box
Translucent- fog and smoke

We cannot see our image in the mirror in complete dark room because there is no light to reflect.

Luminous –sun, stars
Non luminous-moon, table, chair

Objects that give out or emit light of their own are known as luminous objects. For example candle, sun etc. Objects that cannot give out or emit light of their own are known as non- luminous objects. Such as chair, book etc.

We cannot see objects through T shaped or N shaped pipe because light travels through straight line.

To see an object, we need source of light, eyes and object. When light emitted by luminous body falls on an object, it is reflected back and received by our eyes. Then we see that object.

A) Sun b) flame of gas burner.

Moon appears bright in night because it reflects sun light that falls on it.

Transparent and some translucent objects do not cast shadow because light passes through them.

Polished surface cause glares in our eyes because they produce regular reflection of light.

a) Air and water b) polythene and smoke.

Paper, rock and sun.

When an object is placed in path of light, a dark portion is formed on the opposite side of object. This dark portion is shadow.

Optical object by which we can see objects located above our line of sight.