Page 96 - Viva ICSE Science 4 : E-book

TIME TO REVISE

Circle the correct answer.
1. Moon is an example of (luminous/non-luminous object).
2. Stars are (natural/artifi cial) sources of light.

3. Lamp is an example of (natural/artifi cial) sources of light.

Properties of Light

• Light travels in a straight line in the form of rays.
Did You Know!

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• Light travels very fast, at the speed of 3 × 10 m/s (metre Light travels faster
per second). in air than in water
and slower still in
• Light travels in all directions from its source. glass.

• Light can also travel through empty space (vacuum).

• Light can be refl ected. When light rays fall on any surface, it bounces back. This is

called refl ection of light. Objects become visible to us when the refl ected light rays
reach our eyes.

• Light can be refracted/bent.

When light travels through water, air or

glass, it bends and changes its direction
slightly. This is called refraction of light.
That is why a straw, half dipped in liquid,

appears bent at the boundary of water.
Another example of refraction is splitting
of visible light into seven diff erent prism

colours through a glass prism. These colours are violet, indigo, blue, green, yellow,
orange and red. To remember these colours in order, people memorise the word

VIBGYOR.

Transparent, Translucent and Opaque Materials

In our daily lives, we encounter materials that interact with light. Sometimes light passes

through these materials. Some materials allow light to pass through them while some
do not. Based on the amount of light that materials allow to pass through them, they are
classifi ed into transparent, translucent and opaque materials.

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