Class-6 Sciene Chapter-11 Light, Shadows and Reflections

 EVENTS CONVENT HIGH SCHOOL

28/01/2021             CLASS-6                   SLOT-2

SCIENCE 
chapter-11 LIGHT,SHADOWS AND REFLECTIONS
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 1.Rearrange the boxes given below to make a sentence that helps us understand opaque objects.

Ans:

 VERY SHORT ANSWER TYPE QUESTIONS

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

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

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

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

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

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

 
 SHORT ANSWER TYPE QUESTIONS

1. 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.

2. Why is the moon not considered as a luminous body?
Ans: Moon is non-luminous body because it shines by reflecting the sunlight falling on it.

3. What is an incandescent body? Give example.
Ans:  The bodies which emit light when heated to a very high temperature are called incandescent bodies. Example: electric bulb.

4. When does a shadow form?
Ans: Shadow is formed when light does not reach behind the opaque object kept in the path of light

5. Draw a diagram to illustrate the formation of umbra and penumbra.
Ans: 

6. 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.

7. 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.

8. Write difference between shadow and image.
Ans: 

9. How will you convert a glass sheet into a translucent sheet?
Ans: There are following two methods to convert glass sheet into a translucent sheet:
(i) By smearing a thin layer of oil on glass sheet.
(ii) By covering a side of sheet by butter paper.

10. What is shadow? How does the colour of an opaque object affects the colour of the shadow?
Ans: A dark outline or patch formed by an opaque object that blocks light coming from a source of light is called shadow. The colour of an opaque object does not affect the colour of the shadow.

11. Write the differences between umbra and penumbra.
Ans: 

12. What do we need in order to see a shadow?
Ans: We need: (i) A source of light (ii) a screen (in) an opaque object.

13. What do you mean by scattering of light?
Ans: When a beam of light falls on a rough surface it is turned back in different directions. It is called scattering of light.

14. A and B are facing the mirror and standing in such a way that A can see B and B can see A. Explain this phenomenon.

Ans:  The light rays from A falls on the mirror and gets reflected and reaches B, the light from B falls on the mirror and reflects to reach A. The path of light is just reversed as shown.

Extra Question:-

1. What is reflection of light? Explain reflection of light with the help of an activity.
Ans:  When light rays fall on a highly polished (e.g. mirror) smooth surface and return to the same medium, it is called reflection of light.
Activity to show reflection of light: This activity should be done at night or in a dark room. Ask your friend to hold a mirror in his hand at one corner of the room. Stand at another comer with a torch in your hand. Cover the glass of torch with your fingers and switch it on. There should be small gap between your fingers. Direct the beam of torch-light on to the mirror that your friend is holding. Adjust the direction of torch so that patch of light falls on your friend standing in the room. This activity shows the reflection of light also that light travels in straight line.