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Question
What is a rainbow? What are the two conditions necessary for the formation of a rainbow in the sky?
Solution
A rainbow is a natural spectrum of seven colours formed in the sky when the water droplets in the atmosphere cause the dispersion of sunlight. The two conditions necessary for the formation of a rainbow are as follows.
1. The sun should be shining.
2. It should be raining.
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RELATED QUESTIONS
In the following diagram the correctly marked angles are :
(a) ∠A and ∠e
(b) ∠i, ∠A and ∠D
(c) ∠A ∠r and ∠e
(b) ∠A ∠r and ∠D
What are the seven colours seen in a rainbow?
A beam of white light is shone onto a glass prism. The light cannot be:
(a) deviated
(b) dispersed
(c) focused
(d) refracted
State the speed of light in (a) air, (b) water, and (c) glass
The diagram below shows the path taken by a narrow beam of yellow monochromatic light passing through an equiangular glass prism. If the yellow light is replaced by a narrow beam of white light incident at the same angle, draw another diagram to show the passage of white light through the prism and label it to show the effect of prism on the white light.
What conclusion do you draw about the nature of white light in part (b)?
In the spectrum of white light by a prism, the colour at the extreme end opposite to the base of prism is ______.
A student has to trace the path of a ray of light through a glass prism. List four precautions he should observe for better results.
A prism of refractive index `sqrt2` and refracting angle A produces minimum deviation δm of a ray on one face at an angle of incidence 45°, The values of A and δm are, respectively ______.
Make a rainbow
Try to make your own rainbow. You can try this project in the morning or in the evening. Stand with your back towards the Sun. Take a hosepipe or a water pipe used in the garden. Make a fine spray in front of you. You can see different colours of rainbow in the spray.
