CLASS - 4 // SUBJECT - SCIENCE // LESSON 9 // LIGHT //

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LESSON 9

LIGHT


1.         Why do we need light?

We need light. Light helps us to see things, it helps in the formation of mirror images.

 

2.       What are the main sources of light on Earth? Mention the two broad groups with examples.

The main sources of light on Earth can be broadly divided into two groups. They are:-

a.        Natural

b.        Artificial.

a.        Natural sources- Natural sources of light are the sources that emit light on their own. Sun is the main source of natural light on Earth.

b.        Artificial sources- Artificial sources of light that are made by man to produce light. Bulb, torch and table lamp are examples of artificial sources of light.

 

3.       Distinguish between luminous and non-luminous objects

The object that produces light of their own is called luminous objects. Example. candle, tube light etc

The object that do not produce their own light are called non-luminous object. Example. Bed, book table etc.

 

4.       Write any three properties of light.

a.        Light travels very fast

b.        Light travels in a straight line

c.        Light travels in all directions from its source.

 

5.       What are transparent, translucent and opaque objects? Give two examples of each.

a.        Transparent - Objects that let light pass through them are called transparent objects. Example. Clear glass, clear water

b.        Translucent- objects that allow only a little amount of light to pass through them are called translucent objects. Example. Honey, vegetable oil.

c.        Opaque Objects - objects that do not allow any light to pass through them are called opaque objects. Example. Wood, Books

 

6.       How are shadows formed?

When light falls on an opaque object, we see a dark are on the other side of the object. This dark area is called the shadow of the object.

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