Page 108 - Viva ICSE Science 5 : E-book

10 Light and Shadows

Can you see the chair, table, book, or other things KEY CONCEPTS

around you when it’s dark? The answer is no. To
• Light • Shadow
view things, you need a source of light such as
• Rotation and revolution of earth
the sun, bulb, tube light, burning candle or torch.
• Formation of day and night
In this chapter, you will learn more about light • Eclipse
and its signifi cance.

Light

We know that light is a form of energy that enables us to see things. Sun and stars are
natural sources of light. They emit light of their own. Such objects which emit light of
their own are called luminous objects. Some organisms like fi refl y, glow-worm and

lantern fi sh also emit light of their own.

Man-made objects like bulb, tube light, torch and candle also emit light. These are
artifi cial sources of light. These objects are invisible in dark, but you can see them in the

presence of a source of light. Such objects that do not have light of their own, but are
visible when light falls on them are called non-luminous objects.

Objects can also be classifi ed as transparent, translucent and opaque based on the

ability of light to pass through them.

Transparent, translucent and opaque objects

When you look around, you will fi nd that you can see
through a glass window and not through the walls of

your classroom. This is because glass allows light to pass
though it but a wall made of bricks refl ects the light.

Objects that allow light to pass through them completely

are called transparent objects. For example, glass, air and
water are transparent objects.
Glass window (transparent)

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