Monday, 28 December 2020

Chapter 11 Light , Shadows And Reflections



Chapter- 11

Light, shadows and refLection

ACTIVITY- 1: To distinguish transparent, opaque and translucent objects.

Question 1- Classify different objects depending on whether an object allows light to pass through it completely, partially or not at all.

Answer- Transparent, translucent and opaque objects.

Question 2- Classify the objects given in following table as transparent, opaque or translucent.

Object/ Material

Transparent/ Opaque/ Translucent





Tissue Paper















Thin Cloth





ACTIVITY- 2 : To show that light travels in a straight line. (Page No.- 109)

Question 1- Light travels in __________ line path

Answer- Straight.

Question 2- Light cannot pass through _________ material.

Answer- Opaque.


ACTIVITY- 3: To show that screen is compulsory for the formation of shadow.

Question 1- For shadow formation, how many things are required?

Answer- Three i.e. a source of light, an opaque object and a screen.

Question 2- A shadow is observed, on a screen, when an ______ object comes in-between screen and a source of light.

Answer- Opaque.

ACTIVITY- 4: To study factors on which size and colour of shadow depends.

Question 1- The size of shadow of a given opaque object depends on relative _____ of source of light and the opaque object.

Answer- Position.

Question 2- What may be the colour of opaque object, shadow will always be ________. (black/ white)

Answer- Black.


ACTIVITY- 5 : To construct a pinhole camera.


Question 1- Pin hole camera is based on the fact that in ordinary conditions light travel in ____ path.

Answer- Straight line.

Question 2- The images formed by pin hole camera is _______ and ________.

Answer- Inverted and smaller in size.


ACTIVITY- 6 : To observe reflection of lght.


Question 1- A mirror does not change the direction of light that falls on it. (true/ false)

Answer- False.

Question 2- A polished or shining surface like plane mirror produces ___________ reflection.

Answer- Regular.





Question 1- Fill In The Blanks.

a). An object that allow light to pass through them partially are known as translucent objects.

b). Light source like the Sun that emit light of their own are called luminous objects.

c). Never ever look directly at the Sun because it could be extremely dangerous for the eyes.

d). The change in direction of propagation of light when light allowed to fall on polished surface is called reflection of light.

e). Due to reflection phenomena rooms are lighted up in day time though no direct sunlight enters the room.


Question 2- Write True Or False.

a). Moon is a luminous object. (False)

b). We can clearly see through transparent material. (True)

c). Shadow of opaque object is always black. (True)

d). Light doesn’t travel in straight line path. (False)

e). Due to reflection of light, rooms are lighted up during day time though no direct sunlight enters the room. (True)

Question 3- Match The Column ‘A’ With Column ‘B’.

A                                                         B

1. Natural source of light                 a. Light moves along a straight path (3)

2. CFL, LED and tube light              b. Opaque object (5)

3. Rectilinear propagation of light   c. Shadow cast by a heavenly body (4)

4. Eclipse                                          d. Man-made source of light (2)

5. Cardboard, wood and metal         e. Sun, stars and firefly (1)


Question 4. Choose The Correct Answer.


(i). Objects, like moon, which do not emit light of their own, are called

a) Luminous objects

b) Absorbers of light

c) Non-luminous objects ()

d) Reflectors of light


(ii). An object, through which we can see partially, but not very clearly, is

a) A rubber ball

b) A sheet of plane glass

c) A sheet of tracing paper ()

d) A compact disc


(iii). When Sun (during evening) is behind an object, the size of its shadow in comparison to that of the object would be

a) Smaller

b) Larger ()

c) Almost zero

d) Equal


(iv). The image, formed by a pin hole camera, is

a) Inverted and diminished ()

b) Inverted and enlarged

c) Erect and enlarged

d) Erect and diminished


(v). For shadow formation, we require :

a) An opaque object

b) A source of light

c) The screen to obtain the shadow

d) All of the above ()


Question 5- Very Short Answer Type Questions.

(i) State the type of path that light ordinarily follows while going from one point to another.

Answer- Straight line path.


(ii) Fishes do not cast shadow in water. Why?

Answer- Due to absence of a screen at proper distance.


(iii) State the relative position of Sun, Earth and the Moon during solar eclipse.

Answer- During solar eclipse moon is between sun and earth.


 (iv) In a completely dark room, if you hold a mirror in front of you, will you see a reflection of yourself in the mirror?

Answer- No.


(v) Two identical bed sheets, of pink and grey colour are hanging on a rope under the Sun. What would be the colour of shadow of these two bed sheets?

Answer- Black.


Question 6- Short Answer Type Questions.


(i) What is regular reflection?

Answer-When light fall on polished or shining surface like plane mirror, these surfaces reflect light in a well defined regular manner, this is called regular reflection. Sometimes regular reflection also forms images.

(ii) Why shadow in afternoon is smaller than shadow formed in the morning?

Answer- In afternoon the Sun is above the object, So forms a smaller shadow. In morning sunlight falls obliquely and forms larger shadow.


Question 7- Long Answer Type Questions.


(i) Using suitable diagrams show that size of shadow formed, depends on relative position of the source of light and the opaque object.



(ii) Using diagram, show the formation of image by pinhole camera.