- Books Name
- CBSE Class 6 Science Book
- Param Publication
- CBSE Class 6
3. Phenomenon of a mirror changes direction of light that falls on it.
This activity should be done at night or in a dark room. Ask one of your friends to hold a mirror in his/her hand at one corner of the room. Stand at another corner with a torch in your hand. Cover the glass of torch with your fingers and switch it on. Adjust your fingers with a small gap between them so that you can get a beam of light. Direct the beam of the torch light onto the mirror that your friend is holding. Do you see a patch of light on the other side?
Now, adjust the direction of the torch so that the patch of light falls on another friend standing in the room. This activity suggests that a mirror changes the direction of light that falls on it. Here is an activity that shows light travelling along straight lines and getting reflected from a mirror.
4. To prove that smooth and shiny surfaces reflect light better.
• Place objects like a mirror, a shiny steel plate, a plastic plate or a sheet of paper near a screen which can be a wall or a paper sheet.
• Shine a beam of light through a torch on these objects in such a way that reflected light falls on the screen as shown in figure.
You will observe that in case of the plate mirror, a bright patch of light is seen on the screen. Similarly, in case of the steel plate, a patch of light is visible on the screen. But when you use a paper sheet, no patch of light can be seen on the screen.
Shiny and polished objects like steel plate, mirror, polished wood piece, etc. reflect more light and form a brighter patch on the screen. Rough and dull surfaces, on the other hand, reflect less light and do not make a patch on the screen.
5. Phenomenon of shadow formation.
(a) 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.
(b) 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.
(c) Take flowers or other objects of different colours and look at their shadows such as 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.
(d) 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.