SCIENCE CH- LIGHT SHADOWS AND REFLECTION QUESTION BANK

 PODAR INTERNATIONAL SCHOOL, VADODARA

SCIENCE

   CH- LIGHT SHADOWS AND REFLECTION QUESTION BANK

1.   

1.1.Define luminous body.

2.     2.What are luminous and non-luminous objects?

3.     3.Define opaque objects with example.

4.     4.What are translucent objects?

5.    5. What are transparent objects?

6.     6.Classify the following into transparent, opaque and translucent objects:
Wax, spectacles, a heap of salt, a stone, dense smoke, wood, skin, balloon, rubber, membrane of a tabla, blood and milk.

7.     7.Close your eyes while looking towards bright sunshine. Now, cover the eyes with your palm still keeping them closed. Do you notice any difference? On the basis of this experience, state whether your eyelids are transparent, translucent or opaque.

8.    8. Sometimes, you are able to see the Sun or the Moon behind the clouds. What can you say about the ability of such clouds to transmit light? ‘

9.     9.How will you convert a transparent glass sheet into a translucent sheet? Suggest any two ways to do it.

10.  10.List four natural sources of light.

11.  11What do we need in order to see a shadow?

12.  12Does the direction of shadow change during the day? Does the length of shadow also change from season to season?

13.13  What is a shadow? How is it formed? How does the colour of an opaque object affect the colour of the shadow?

14. 14. What is a shadow? How is it formed? How does the colour of an opaque object affect the colour of the shadow?

15.  Activity 4
Place a chair in the school ground on a sunny day. What do you observe from the shadow of the chair?
Does the shadow give an accurate picture of the shape of the chair? If the chair is turned around a little, how does the shape of the shadow change?
No, accurate shape of chair is not shown by the shadow. When turned around a little, the shape of the shadow will change because now different portions of the chair will obstruct light and make shadow.

Take a thin notebook and look at its shadow. Then, take a rectangular box and look at its shadow. Do the two shadows seem to have a similar shape?
Yes, the two shadows seem to have a similar shape.

Take flowers or other objects of different colours and look at their shadows. A red rose and a yellow rose, for instance. Do the shadows look different in colour, when the colours of the objects are different?

         No, the shadows of the different coloured objects are not different.

Take a long box and look at its shadow on the ground. When you move the box   around, you may see that the size of the shadow changes. When is the shadow of the box the shortest, when the long side of the box is pointed towards the Sun or when the short side is pointing towards the Sun?
Shadow of the box is the shortest when the short side is pointing towards the Sun.

16.  A Pinhole Camera

Define pinhole camera.
Answer:
It is a device which forms a photograph like image of a bright object on a screen.

Can you think of a situation where we can see the path of the light?
Answer:
In a dark room, we can see with torch light which goes straight. Similarly, dust particles become visible when light enters the room through fine hole.
All these examples indicate that light travels in straight line.

Why is the image formed in a pinhole camera inverted?
Answer:
In a pinhole camera, image formed is inverted because the object is between radius of curvature and focus.

What is the path of light?
Answer: Straight line.

Mirrors and Reflections

Question 1.
What is reflection?
Answer:
When a ray of light falls on a smooth and shiny surface, the whole of light is sent back in the same medium. It is called reflection. Mirrors do not allow even a small amount of light to pass through them. Mirrors show regular and complete reflection.

Fill in the blanks with appropriate words:

a)     An object or material could be opaque, transparent, translucent or ………………..

b)     .This is a …………… on which the shadow is formed.

c)     A …………….. is a dark outline of an opaque object that blocks light coming from a source.

d)     Image formed by a pinhole camera is ………………..

e)     Image formed by a plane mirror is …………….. .

f)      In a plane mirror, our left hand looks like right hand. This phenomenon is called ……………………… .

g)     ……………… objects cast no shadow.

h)     Opaque objects cast …………………. shadows in morning and evening while ………………… shadows at noon.

i)       Light travels in a ………….. .

j)       Shadow is …………… .

Answers:

luminous

screen

shadow

upside down

erect

lateral inversion

Transparent

big, small

straight line

three dimensional

State whether the statements given below are True or False:

a)     A torch bulb is a luminous object.

b)     Light travels in a straight line.

c)     Image formed by a plane mirror is inverted.

d)     Light gets reflected when strikes a shiny surface.

e)     Transparent substances reflect all the light falling on them.

f)      All the shining bodies in sky have their own light.

g)     Jugnu (Firefly) is a living luminous body.

h)     When screen is far away from the objects, the shadow will have no penumbra.

i)       A reflected image gives us more information about the object than a shadow.

j)       In a mirror, if A is able to see B, B also can see A.

k)     Objects around us seem to have different ways in which they interact with light.

Answers:

1.     True

2.     True

3.     False

4.     True

5.     False

6.     False

7.     True

8. False
9. True
10. True
11. True

 

Choose the correct option in the following questions:

(i)               Light travels in
(a) straight line
(b) curved line
(c) zig-zag line
(d) randomly

Answer:
(a) Light travels in straight line.

(ii) When an opaque object comes in the path of light it forms
(a) an image with colours
(b) shadow
(c) black and white image
(d) depends on the colour of the light
Answer:
(b) A shadow is formed when an opaque object comes in the way of light.

(iii) Which types of objects do not allow light to pass through them?

(a)   Translucent
(b) Opaque
(c) Transparent
Answer:
(b) Opaque objects do not allow the light to pass through them while translucent objects allow only a part of light to pass through them.

 

(iv) Which is an example of a translucent object?
(a) A thin sheet of paper
(b) A thin glass slab

(c) A thin iron sheet
(d) All of these
Answer:
(a) A thin sheet of paper is transparent.

(v) What is lateral inversion?
(a) Image becomes inverted
(b) Image bends laterally
(c) Right of the object appears left of the image
(d) All of these happen
Answer:
(c) Right side of the object appears as left side in the image formed by a plane mirror.

(vi) Which letters of English alphabet will not show lateral inversion?
(a) I, O, U
(b) N, Z, X
(c) I, X, E

(d) A, E, I
Answer:
(a) I, O, U will not show lateral inversion.