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प्रश्न
State the conditions when only the penumbra of an opaque object is obtained on the screen.
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 .................
Select the correct alternative.
Umbra is a region of
State two differences between an umbra and a penumbra.
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In the following diagram, draw rays to form umbra on the screen.
What are the essential conditions for the formation of shadow?
How does the colour of an opaque object affect the colour of the shadow?
What do we need in order to see a shadow?
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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 Fig. 11.7 are switched on one by one. The light from which of the torches will not form a shadow of the ball on the screen.
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The shape of the shadow obtained in two positions is shown in Fig. 11.10
Match the position of the torch and shape of the shadow of the ball.
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.
