22 February 2015

CBSE-NCERT Solution : Light, Shadows and Reflections

CBSE NCERT Class VI (6th) | Science | Physics

Chapter  :  Light, Shadows and Reflections

CBSE NCERT Solved Question Answer

Ql. Does the flame of a gas stove emit light?

Q2. What is rectilinear propagation of light?
Light travels in a straight line.

Q3. Write the names of 4 different sources of light?
Bulb, sun, stars, firefly

Q4. Give one example of living thing which emits light?
Jugnu {firefly)

Q5. Sometimes you are able to see sun or moon behind the clouds .What can you say about the ability of such clouds to transmit light?
Yes, clouds transmit light.

Q6. Image formed in a pinhole camera is inverted .Why?
It is inverted because of the rectilinear propagation of light.

Q7. Can you suggest the shape of the shadows?
It is usually similar to the object.

Q8. Does the length of shadow change from season to season?
Yes if observed at same time .

Q9. What is shadow?
A dark patch formed behind an opaque object when it is placed in the path of light.

Qll. What do you mean by reflection of light?
Coming back of light ray incident on a surface is called reflection.

Ql2. What is the principle of working f a pin hole camera?
A pinhole camera is based on rectilinear propagation of light? 

Ql3. Can light pass through opaque objects?

Ql4. What is an artificial source of light?
Man made sources of light. For example: electric bulb, candle etc.

Ql5. Classify the following into transparent, translucent, and opaque objects.
{Glass, air, oil paper, rubber sheet)

Transparent: air, glass     Translucent: oil paper     Opaque: rubber sheet 

Ql6. Name two artificial sources of light?
Electric bulb, candle

Ql7. Name one transparent and one opaque body?
Transparent: air Opaque: stone

Ql8. Define reflection of light?

The process of returning {Or bouncing back) the light to the same medium after Striking a surface is called reflection of light.

Q19. What is a reflector?
A surface which reflects the light is called reflector. 

Q20. Give one example of most commonly used reflector?
Looking glass or plane mirror

Q21. Does the reflection of light from the surface similar to the bouncing back of a rubber ball after it strikes from a ball? Explain.
Yes, because of reflection, light falling on a surface bounces back to the same medium.

Q22. Give the properties of the image formed by the pane mirror?
l. The image formed by plane mirror is erect and virtual.
1.   Size of the image formed by plane mirror is equal to the size of the object.
2.   The distance of the image behind the plane mirror is equal to the distance of the object from the mirror.
CBSE NCERT Class VI (6th) | Science |  | Physics, Light, Shadows and Reflections,  CBSE NCERT Solved Question Answer, CBSE NCERT Solution.
Q23. Define luminous objects?
The objects which emit light are called luminous objects.

Q24. What is light?
Light is a form of energy which produces the sensation of sight.

Q25. What are non luminous objects?
Objects which do not emit their own light.

Q26. Why do objects in a room become visible even if sunlight does not enter it?
The objects in a room become visible, even if the sunlight does not enter the room because the air around the objects allows the scattered light to pass through it and we can see the objects.

Q27. How can you convert a transparent glass sheet into a translucent glass sheet?
By covering one side with butter paper.

Q28. Does the colour of the shadow depend upon the colour of the object?
No, it is always dark.

Q29. 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?
No, because there is no source of light .We can see our image only when light is reflected from the mirror.

Q30. Give few examples of opaque, translucent and transparent objects?
Opaque: a piece of rock, a sheet of aluminium, a mirror, a wooden board, a wall a sheet, a sheet of cardboard, a CD
Translucent: a sheet of polythene , smoke, fog, a sheet of carbon, a sheet of cellophane.
Transparent: air, water, a sheet of plane glass QlS. What do you understand by lateral inversion?
The right side of the object appears to be the left side of its image and vice-versa This is called lateral inversion.

Q31. Give one example to show that light travels in a straight line?
When sunlight falls on a solid object like a building or a stone, a shadow is formed behind the solid object {opaque object) .This shows that light travels in a straight line.

Q32. Distinguish between transparent, translucent and opaque materials?
Transparent materials: which allow light to pass through them and through which we can see clearly are known as transparent materials.
Translucent materials: substances through which light can pass partially and through which we can't see clearly are called translucent materials.

Opaque materials: substances which don't allow light to pass through them at all
are called opaque materials.

Q33. Can the opaque object cast shadow?
In the presence of light, opaque objects act as obstacles to propagate {travel) light
and form a shadow behind them

Q34. How are shadows formed?
Light coming from the source of light falling on the objects gets obstructed by the objects and does not go ahead. So, a shadow is formed.

Q35. How can we protect our eyes while glaring at a strong source of light?
By placing our hand in front of our eyes, light coming from the source does not fall on our eyes directly. {Since we know light travels in a straight line.)

Q36. What happens when light falls on an object?
l. It is almost completely transmitted through the object.
a)    Only one part of it may be transmitted and the rest is absorbed or spread out.
b)    It may not be allowed to pass through at all.

Q37. Consider a wooden stick about half a meter long. Fix one end of it in open ground where there are no trees and buildings near it. Look its shadow in the morning and mark its points of shadow. Note the direction of sun with respect to stick. Where is shadow of the object formed?
The shadow of the object is formed in the direction opposite to the side of the source light i.e. it is formed opposite to the direction of the sun. This activity also shows   that shadow moves according to the movement of the sources of light and the length of the shadow changes with time and the shadow of an object is formed in the direction opposite to that of the source of light.