How is shadow formed?
Shadow
tree shadow
Have you seen your black friend who always walks with you, sleeps with you and eats with you?
All of you have got such a friend. It is your shadow.
How is shadow formed?
Shadow is an area of darkness. Shadow is formed when the light is stopped by an object.
Can you say which objects stop light? Try with an apple, a book, a glass or a flower.
Objects which let light pass through them are called transparent objects.
Shadow change in length and direction
The length and direction of the shadow is changes with changes in position and direction of source of light. You observe daily that tour owns shadow changes its length and direction with time during the day. In the morning, the sun is in the east and low. Your shadow is long towards west. At noon, the sun is overhead. The shadow is very small. In the evening the sun is in the west and low. The shadow is again longer and is towards west. What do you conclude? The length and direction of shadow is changes with opposite surface to the direction of the sun. Also the shadow is always on the opposite surface to the direction of the source of light.
You will find that shape of shadow is similar to the shape of the body.
Se we can conclude that size of shadow depends upon the position of object and source of light. The shape of the shadow is similar to that of the object.
Do you know?
* Shadow used to help people tell the time when there were no clocks. They used sundials.
You can also make a sundial. Cut out circle of white card. Push a splinter through the center. Stick the splinter into the ground. Mark where is the splinter shadow falls on the paper each hour. You can use this clock from the next day.
Experimental -I
- Take a torch. Cover its glass with dark paper having a narrow hole in the middle. Hang a ball between the torches and see that light falls on the ball. You will find the shadow of the ball on the wall. Now shift the ball close to the torch. What do you find? You will find that shadow becomes bigger. Now shift the torch away from the ball.
What do you find/ you will find that shadow becomes smaller. Repeat the above activity with different bodies in front of the torch having different shapes.
Experimental –II
- You can make a shadow picture of your friend. Paste a white paper on the wall, and let your friend sit close to it. Switch on the torch and shine the wall, and let your friend sit close to it. Switch on the torch and shine it towards him. Now you could see his shadow on the paper. Ask another friend to outline the shadow with a pencil.
After finishing the outline, you can take the paper from the wall, and fill the outline with colors. Draw the shadow portrait of your father, mother and the other members of your family. You can keep them in your shadow album.
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