NCERT Class 6 Science Light Shadows and Reflections

NCERT Class 6 Science Light, Shadows and Reflections. Download NCERT Chapters and Books in pdf format. Easy to print and read. Copies of these textbooks may be downloaded and used as textbooks or for reference. Refer to other chapters and books at other links (NCERT now providing you soft copies of all textbooks of all subjects from class first to twelfth online). 

Light, Shadows and Reflections

We see so many objects around us, colourful and different. On the way to school we see things like buses, cars, cycles, trees, animals and sometimes flowers. How do you think, we see all these objects? Think of the same places at night time if it were completely dark. What will you see? Suppose you go inside a completely dark room. Are you able to see any objects in the room? But, when you light a candle or a torch you can see the objects present in the room, isn’t it? Without light, things cannot be seen. Light helps us see objects.

The torch bulb is an object that gives out light of its own. The Sun, is another familiar object that gives its own light. During the day, its light allows us to see objects. Objects like the sun that give out or emit light of their own are called luminous objects. What about objects like a chair, a painting or a shoe? We see these when light from a luminous object (like the Sun, a torch or an electric light) falls on these and then travels towards our eye.

11.1 TRANSPARENT, OPAQUE AND TRANSLUCENT OBJECTS

Recall our grouping objects as opaque, transparent or translucent, in Chapter 4. If we cannot see through an object at all, it is an opaque object. If you are able to see clearly through an object, it is allowing light to pass through it and is transparent. There are some objects through which we can see, but not very clearly. Such objects are known as translucent.

Activity 1

Look around you and collect as many objects as you can — an eraser, plastic scale, pen, pencil, notebook, single sheet of paper, tracing paper or a piece of cloth. Try to look at something far away, through each of these objects (Fig. 11.1). Is light from a far away object able to travel to your eye, through any of the objects? Record your observations in a table as shown in Table 11.1. We see that a given object or material could be transparent, translucent.

11.2 WHAT EXACTLY ARE SHADOWS?

Activity 2

Now, one by one hold each of the opaque objects in the sunlight, slightly above the ground. What do you see on the ground? You know that the dark patch formed by each on the ground is due to its shadow. Sometimes you can identify the object by looking at its shadow (Fig. 11.2).

Spread a sheet of paper on the ground. Hold a familiar opaque object at some height, so that its shadow is formed on the sheet of paper on the ground. Ask one of your friends to draw the outline of the shadow while you are holding the object. Draw outlines of the shadows of other objects in a similar way. Now, ask some other friends to identify the objects from these outlines of shadows. How many objects are they able to identify correctly? Do you observe your shadow in a dark room or at night when there is no light? Do you observe a shadow when there is just a source of light and nothing else, in a room? It seems we need a source of light and an opaque object, to see a shadow. Is there anything else required?

Activity 3

This is an activity that you will have to do in the dark. In the evening, go out in an open ground with a few friends. Take a torch and a large sheet of cardboard with you. Hold the torch close to the ground and shine it upwards so that its light falls on your friend's face. You now have a source of light that is falling on an opaque object. If there were no trees, building or any other object behind your friend, would you see the shadow of your friend's head? This does not mean a building, or other such surfaces act as a screen for the shadows you observe in everyday life.

Shadows give us some information about shapes of objects. Sometimes, shadows can also mislead us about the shape of the object. In Fig. 11.4 are a few shadows that we can create with our hands and make-believe that they are shadows of different animals. Have fun!

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? 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? 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? 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? Let us use this long box, to prepare a simple camera.

11.3 A PINHOLE CAMERA

Surely we need a lot of complicated stuffto make a camera? Not really. If we just wish to make a simple pin hole camera.

Activity 5

Take two boxes so that one can slide into another with no gap in between them. Cut open one side of each box. On the opposite face of the larger box, make a small hole in the middle [Fig. 11.5 (a)]. In the smaller box, cu out from the middle a square with a sideof about 5 to 6 cm. Cover this opensquare in the box with tracing paper (translucent screen) [Fig. 11.5 (b)]. Slide the smaller box inside the larger one with the hole, in such a way that the side with the tracing paper is inside [Fig. 11.5 (c)]. Your pin hole camera is ready for use.

Exercises 

1. Classify the objects or materials given below as opaque, transparent or translucent and luminous or non-luminous:

Air, water, a piece of rock, a sheet of aluminium, a mirror, a wooden board, a sheet of polythene, a CD, smoke, a sheet of plane glass, fog, a piece of red hot iron, an umbrella, a lighted fluorescent tube, a wall, a sheet of carbon paper, the flame of a gas burner, a sheet of cardboard, a lighted torch, a sheet of cellophane, a wire mesh, kerosene stove, sun, firefly, moon.

2. Can you think of creating a shape that would give a circular shadow if held in one way and a rectangular shadow if held in another way?

3. 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?


Please refer to attached file for NCERT Class 6 Science Light, Shadows and Reflections

Tags: 

 


Click to View or Download pdf file
Click for more Science Study Material

Latest NCERT & CBSE News

Read the latest news and announcements from NCERT and CBSE below. Important updates relating to your studies which will help you to keep yourself updated with latest happenings in school level education. Keep yourself updated with all latest news and also read articles from teachers which will help you to improve your studies, increase motivation level and promote faster learning

CBSE Board Exams in July Press Release

CBSE has released press note for the dates for the CBSE Board exams for Class 10. CBSE said “With regards to conduct of Class X examinations several queries are being received by the CBSE. In this context, it is once again reiterated that remaining examinations of...

Class 10 Datesheet announced

CBSE has announced the date sheet for the remaining class 10 Board Exams, see dates below

Board Cancelled Official CBSE Statement

Keeping in view the requests received from various State Governments and the changed circumstances as on date, following has been decided- 1. Examinations for classes X and XII which were scheduled from 1st July to 15th, 2020 stand cancelled. 2. Assessment of the...

Board Exams Class 10 and Class 12 Datesheet 2020

CBSE has announced the datesheet for the remaining exams of class 10 and class 12 exams. The exams are going to start in July. The class 10 and 12th board exams will be conducted for the remaining 29 papers from July 1 to July 15, 2020, at various centers nominated by...

Class 12 Board Exams Datesheet Announced

CBSE has announced the datesheet of the remaining class 12 board exams, see below:  

CBSE Decision on Board Exam 2020

The Class 10 and 12 exams are cancelled, and results for both 10th and 12th would be declared by July 15 based on internal exams. CBSE Class 12 students would have the option to appear for the exams at a later date. CBSE has a scheme in which marks scored in past 3...

×
Studies Today