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प्रश्न
State the conditions when only the penumbra of an opaque object is obtained on the screen.
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उत्तर
If the size of the source of light is bigger than the size of the opaque object, the size of the umbra is very small. If the screen is moved away from the object, the umbra vanishes and only the penumbra remains.
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संबंधित प्रश्न
Fill in the blank.
The less dark portion of a shadow is called the .................
What is a shadow? Give a reason for its formation.
Draw a ray diagram to show the formation of umbra and penumbra both. Label the parts umbra and penumbra in your diagram.
Why is it that the birds flying in the sky do not cast their shadow on the earth?
Tick the correct answer.
Umbra is a region of
When does a shadow form?
What are the essential conditions for the formation of shadow?
What do we need in order to see a shadow?
What is a shadow? What things are necessary for the formation of 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 |
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.
On a sunny day, does a bird or an aeroplane flying high in the sky cast its shadow on the ground? Under what circumstances can we see their shadow on the ground?
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 football match is being played at night in a stadium with flood lights ON. You can see the shadow of a football kept at the ground but cannot see its shadow when it is kicked high in the air. Explain.
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.
