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प्रश्न
Answer the following.
How is a shadow formed? Write the conditions required for a shadow to form.
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उत्तर
Whenlightfallsonanopaqueobject, light is obstructed and a dark patch on a screen kept behind is called the shadow. This is because light propagates in a straight line.
If the distance between the object and screen is less, the shadow will be (umbra) dark and smaller.
If the distance is increased shadow will be dim and larger.
Conditions Required for a shadow to form are:
- There should be a source of light.
- An opaque object.
- A screen.
- The opaque object is placed between the source of light and the screen.
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संबंधित प्रश्न
Fill in the blank.
The darkest portion of a shadow is called the ................
Fill in the blank.
The less dark portion of a shadow is called the .................
Select the correct alternative.
Umbra is a region of
Select the correct alternative.
Penumbra is a region of
Draw a ray diagram to show the formation of the shadow of an opaque object by a point source of light. How is the size of shadow affected if the screen is moved away from the object?
In the following diagram, draw rays to form umbra on the screen.
Why is it that the birds flying in the sky do not cast their shadow on the earth?
What is penumbra?
What do we need in order to see a shadow?
Rearrange the boxes given below to make a sentence that helps us understand opaque objects.
| O W S | A K E | O P A Q | U E O | B J E T | T S M |
| S H A D |
______ is always against, opposite side of light source.
The lighter shade of shadow is the ______.
Three torches A, B and C shown in the following figure are switched on one by one. The light from which of the torches will not form a shadow of the ball on the screen.
Correct the following statements.
- The colour of the shadow of an object depends on its colour of the object.
- Transparent objects allow light to pass through them partially.
A torch is placed at two different positions A and B, one by one, as shown in the following figure.
The shape of the shadow obtained in two positions is shown in the following figure.
Match the position of the torch and shape of the shadow of the ball.
Three identical towels of red, blue and green colour are hanging on a clothes line in the sun. What would be the colour of shadows of these towels?
A student had a ball, a screen and a torch in working condition. He tried to form a shadow of the ball on the screen by placing them at different positions. Sometimes the shadow was not obtained. Explain.
