Page 115 - Viva ICSE Science 5 : E-book

TERMS TO KNOW

1. Luminous objects: Objects which emit light of their own
2. Non-luminous objects: Objects that do not have light of their own, but are visible when
light falls on them
3. Transparent objects: Objects that allow light to pass through them completely

4. Opaque objects: Objects that do not allow light to pass through them
5. Translucent objects: Objects that allow only partial light to pass through them
6. Axis: An imaginary line running through the centre of the earth
7. Rotation: The circular movement of the earth on its axis

8. Orbit: The fi xed path on which the earth moves around the sun
9. Revolution: The movement of earth around the sun on its orbit
10. Eclipse: The partial or total blocking of the light of the sun by a heavenly body like the
earth or the moon

QUICK LOOK

1. To view things, you need a source of light such as the sun, bulb, tube light, burning candle
or torch.
2. Sun and stars are natural sources of light.

3. Bulb, tube light, torch and candle are artifi cial sources of light.
4. Objects can also be classifi ed as transparent, translucent and opaque based on the ability
of light to pass through them.
5. A shadow is formed when the path of light is obstructed by an opaque object.

6. Shadow of an object is formed only in the presence of a source of light.
7. The rotation of the earth on its axis causes day and night.
8. The earth completes one revolution around the sun in 365¼ days.

9. An eclipse is the partial or total blocking of the light of the sun by a heavenly body like the
earth or the moon.

EXERCISES

A. Fill in the blanks.

1. Objects can also be classifi ed as __________, __________ and __________

based on the ability of light to pass through them.

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