Light, Shadows and Reflections

NCERT Revision Notes for Chapter 11 Light, Shadows and Reflections Class 6 Science

CBSE NCERT Revision Notes

1

Topics in the chapter

Answer

  • Light
  • Luminous objects
  • Non-Luminous objects
  • Transparent, Opaque and Translucent Objects
  • Characteristics of light
  • Shadow and its properties 
  • Pinhole camera
  • Mirror and types of mirror
Exercise

2

Light

Answer


→ It is a form of energy which is responsible for seeing objects.

→ When light falls on an object, some light get reflected, this reflected light come to our eyes and we are able to see an object.

→ Example: sun, torch, candle, fireflies and glow worm etc.

Exercise

3

Sources of light

Answer


(i) Luminous object: The objects which emit their own light is called luminous object.

→ Example: sun, torch bulb, star


(ii) Non-luminous object: The objects which do not emit their own light is called non-luminous object.

→ Example: Moon, shoe, trees.

Exercise

4

Types of materials transmit light

Answer


→ There are three types of materials which transmit light:

(i) Transparent

(ii) Translucent

(iii) Opaque


(i) Transparent

→ These objects allow light to pass through them in straight line completely.

→  We can see through these objects clearly.

→  Examples: air, water, etc.


(ii) Translucent

→ These objects allow light to pass through them partially.

→ The object is not clearly seen in translucent object.

→ Examples: Tissue paper, frosted glass, butter paper, etc.


(iii) Opaque

→ These objects do not allow light to pass through them.

→ We can’t see the object through this.

→ Examples: wall, door, trees etc.

Exercise

5

Characteristics of light

Answer


→ Light travels in straight line

→ Light can be reflected

→ Light can be bent

→ The speed of light is 3 × 108 m/sec

→ Light can be polarized

Exercise

6

Shadow

Answer


→ When an opaque object blocked the path of light it forms a dark portion on the opposite side of the object this dark portion is known as shadow. 

Properties of shadow

→ The object must be opaque or translucent

→ Transparent object do not make shadow

→ It is dark in color

→ It is formed opposite to the source of light

→ It gives the information about the shape of object

→ Size of shadow can be increase or decrees by change in distance between object and screen are changed.

Exercise

7

Pin hole camera

Answer


→ It is a toy device use to study light travels in straight line


Properties of image formed by a Pin Hole Camera

(i) Image formed by a pin hole camera is coloured.

(ii) Image formed by a pin hole camera is inverted.

(iii) Image formed by a pin hole camera is smaller in size.

Exercise

8

Rectilinear propagation of light

Answer


→ Light travels in a straight line are called rectilinear propagation of light.


Important terms regard rectilinear propagation of light

(i) Ray of light: It is a path along which light travels in the given direction.

(ii) Beam of light: Bunch of ray of light travel in the given direction.


Exercise

9

Mirror

Answer


→ A mirror is a polished surface which can make the image of an object.


Types of Mirror

(i) Plane mirror: Image formed is of the same size

(ii) Concave mirror: Reflecting surface is bent–in.

(iii) Convex Mirror: Reflecting surface is bulged-out.

Exercise

10

Reflection

Answer


→ When light falls on a mirror, light wave may change their direction upon the striking surface this phenomena is called reflection. It is governed by Laws of Reflection. 
Exercise