Rainbow Questions

A rainbow is a spectacular phenomenon we witness in nature. It is a multi-coloured arc formed by light. When the sunlight enters the water droplet, it undergoes refraction at the surface. When these rays hit the other end of the droplet, they get internally reflected, dispersing into seven colours. Therefore, we can say that the formation of a rainbow is the combination of various phenomena like internal reflection, refraction, and dispersion.

Formation of Rainbow

• Light rays reach the drop near its top level.
• Refraction takes place when the light strikes the water droplet.
• Dispersion of white light into colours of a different wavelength occurs after refraction..
• The order of dispersion of colours is violet, indigo, blue, green, yellow, orange, and red (VIBGYOR).
• Violet is the most deviated colour, and red is the least deviated colour..
• Reaching the opposite side of the drop, each colour is refracted back into the drop due to the complete internal reflection that hits the drop surface.
• Every colour is again refracted into the air.
• The light is bent at different angles.
• This electromagnetic spectrum is composed of different wavelengths of light reflected at various angles.

When the light is reflected twice on the inside of the droplet before leaving it, a double rainbow is formed. A second arc is seen outside the primary arc. In the double rainbow, the order of its colours is reversed, where the red colour appears on the inner side of the arc.

Important Rainbow Questions with Answers

1. Can we obtain a rainbow using a prism?

Answer: Yes we can obtain a rainbow using a prism. When the white light moves through the two faces of the prism, it produces different colours of light that bend at different angles like a rainbow.

2. The rainbow is observed in the direction _____.

1. Opposite of the Moon
2. Opposite of the Sun
3. As the Sun
4. None of the options

Answer: b) Opposite of the Sun

Explanation: The formation of the rainbow takes place in the direction opposite the Sun.

3. In the double rainbow condition, how many times is the light being reflected?

1. One
2. Two
3. Three
4. Four

Answer: b) Two

Explanation: In the double rainbow condition, light is reflected twice.

4. What is the critical angle of a rainbow?

1. 20 degrees
2. 30 degrees
3. 35 degrees
4. 48 degrees

Answer: d) 48 degrees

Explanation: The critical angle of a rainbow is 48 degrees.

5. Fill in the blanks: Stars twinkle due to the _____

1. Atmospheric reflection
2. Atmospheric scattering
3. Atmospheric refraction
4. None of the options

Answer: c) Atmospheric refraction

Explanation: Stars appear higher than they actually are and twinkle due to the atmospheric refraction.

6. Choose the least deviated colour.

1. Violet
2. Blue
3. Red
4. Green

Answer: c) Red

Explanation: Red is the least deviated colour in the rainbow spectrum.

7. Which is the most deviated colour?

1. Violet
2. Blue
3. Red
4. Green

Answer: a) Violet

Explanation: Violet is the most deviated colour in the rainbow spectrum.

8. Rainbow occurs due to which phenomena?

1. Reflection
2. Dispersion
3. Refraction
4. All of the above options

Answer: d) All of the above options

Explanation: Reflection, refraction, and dispersion are the phenomena responsible for the formation of the rainbow.

9. State TRUE or FALSE: When the starlight enters the Earth’s atmosphere, they bend.

1. TRUE
2. FALSE

Answer: a) TRUE

Explanation: This happens due to atmospheric refraction.

10. Fill in the blanks: Refractive index of seawater is _____ rainwater.

1. same as
2. higher than
3. lower than
4. none of the options

Answer: b) higher than

Explanation: The refractive index of seawater is higher than rainwater. Therefore, the radius of the true rainbow is more than the rainbow in sea spray.

Practice Questions

1. Explain the formation of a rainbow using the prism.
2. What is a rainbow?
3. Explain in detail the formation of a rainbow in the atmosphere.
4. Which are the various phenomena responsible for the formation of a rainbow?
5. Give some examples of atmospheric refraction.

Rainbows are considered to be one of nature’s most spectacular gifts. They have also inspired many poems, songs, and other types of art. What is it about these gorgeous arches that make us love them so much? How are rainbows formed? Where does the rainbow end? Let us find out answers to these questions by watching the video.

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