CLASS - 6 || SUBJECT - SCIENCE || Chapter 11 || Light Shadows and Reflection||

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 Chapter 11

Light Shadows and Reflection

 

1.   In a completely dark room, if you hold up a mirror in front of you, will you see a reflection of yourself in the mirror?
Ans: No, in a completely dark room no image will be formed because there is no light in the room so no reflection of light takes place and no image will be formed.

2.  Whether the moon is luminous or non-luminous body?
Ans: Moon is non-luminous body.

3.  What is umbra?
Ans: Umbra is the dark region behind object facing light which does not receive light at all.

4.  How does a light ray travel?
Ans: Light ray travels in a straight line.

5.  Give one natural source of light. 
Ans: Sun is a natural source of light.

6.  What is shadow? 
Ans: Shadow is the dark space behind an opaque object where light does not reach.

7.  What is penumbra?
Ans: The less darker shadow formed penumbra.on the periphery of dark shadow is called penumbra.

8.   State difference between a luminous and a non-luminous body.
Ans: The bodies which emit light are called luminous bodies. Example: sun, stars, burning candle etc.
The bodies which does not emit light are called non-luminous bodies. Example: moon, earth, blackboard.

9.  What are the essential conditions for the formation of shadow?
Ans:
(1) There should be an opaque material.
(2) There should be a source of light and screen.
The object must be placed in the path of light. Then shadow is formed on the screen.

10.            Define reflection of light.
Ans: When light rays after striking the smooth and shiny surface return to same medium, this phenomenon is called reflection of light.

 

11.Explain that light has the property of rectilinear propagation.
Ans: We take three pieces of cardboard. Place them one on the top of one another and make a hole in the middle of each cardboard by using a thick nail. Erect these cards up on the table at a short distance away from each other. Take a candle which is of the same height as the holes in the cards. Light the candle and place it in front of the cards. We see that the light of candle is visible only when the holes on cards lie in a straight line. If we disturb them the light of candle disappears.

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