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Questions
Explain how the formation of a rainbow occurs.
Explain the phenomenon of rainbow formation in the sky. Draw the labelled ray diagram in support of your explanation.
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Solution
- The beautiful phenomenon of the rainbow is a combination of different phenomena, such as dispersion, refraction, and reflection of light.
- The rainbow appears in the sky after a rain shower.
- The water droplets act as small prisms.
- When sunlight enters the water droplets present in the atmosphere, they refract and disperse the incident sunlight.
- Then they reflect it internally within the droplet and finally refract it again.
- As a collective effect of all these phenomena, the seven coloured rainbows are observed.
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Name the phenomenon responsible for the following effect:
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List four characteristics of the image formed by a concave lens of focal length 20 cm when the object is placed at a distance of 40 cm from its optical centre.
The size of image of an object by a convex lens of focal length 20 cm is observed to be reduced to `1/3` rd of its size . Find the distance of the object from the optical centre of the lens .
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Due to _______ pencil looks bent in water, in the given experiment.
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Why a pencil partly immersed in water appears to be bent at the water surface.
