Which of the following phenomena of light are involved in the formation of a rainbow ?a)Reflection, refraction and dispersionb)Refraction, dispersion and scatteringc)Refraction, dispersion and internal reflectiond)Dispersion, scattering and refractionCorrect answer is option 'C'. Can you explain this answer?

Question

Answer

Answer

As you know that a rainbow is a natural spectrum appearing in the sky after a rainbow shower. It is caused by dispersion of sun by tiny water droplets, present in the atmosphere. A rainbow is always formed   in a direction opposite to that of the Sun. The water droplets act like small prisms. They refract and disperse the incident sunlight, then reflect it internally, and finally refract it again when it comes out to the raindrop. Due to the dispersion of light and internal reflection, different colours reach the observer's eye.

Answer

Consider a water drop to be spherical in shape. When light rays from sun enter the water droplet it undergoes refraction at the first surface. As you know white light consists of seven colours they get dispersed after the refraction to the extent which is inversely proportional to their wavelength (like red light gets least dispersed). After the dispersion has occured these different colours hit the other surface of the water droplet and undergo total internal reflection there. Not all light rays produce rainbow. Only those rays whose incident angle is such that the, angle of incidence at the other surface will be greater than critical angle, will produce rainbow.

Answer

C is correct option

Answer

Formation of a Rainbow

A rainbow is a beautiful natural phenomenon that occurs when sunlight is refracted, dispersed, and internally reflected within raindrops in the atmosphere. The formation of a rainbow involves several phenomena of light, namely:

1. Refraction:
When light travels from one medium to another (e.g., from air to water or vice versa), it changes direction. This change in direction is called refraction. In the case of a rainbow, sunlight enters a raindrop and slows down as it moves from air to water. This causes the light to bend or refract, separating the different colors of light.

2. Dispersion:
Dispersion refers to the separation of white light into its constituent colors. White light is a combination of all the colors of the visible spectrum. When light is refracted inside a raindrop, the different colors of light bend at slightly different angles due to their different wavelengths. This causes the different colors to spread out and form a spectrum.

3. Internal Reflection:
After being dispersed inside the raindrop, the different colors of light undergo internal reflection. Some of the light is reflected off the inner surface of the raindrop, while the rest continues to refract and exit the raindrop. The reflected light undergoes another refraction as it exits the raindrop, leading to further dispersion and separation of colors.

Why Option C is the Correct Answer

The correct answer to the question is option C: Refraction, dispersion, and internal reflection. This is because all three phenomena are involved in the formation of a rainbow.

- Refraction: Refraction occurs when light enters and exits the raindrop, causing it to bend or change direction.
- Dispersion: Dispersion happens when the different colors of light separate due to their different wavelengths.
- Internal Reflection: Internal reflection occurs when some of the light is reflected off the inner surface of the raindrop, contributing to the formation of a rainbow.

The other options mentioned in the question are not entirely accurate:
- Option A includes reflection, which is not a significant factor in the formation of a rainbow.
- Option B includes scattering, which is not a primary phenomenon in rainbow formation.
- Option D includes scattering instead of internal reflection, which is not the case in rainbow formation.

Therefore, option C provides the most accurate and complete combination of phenomena involved in the formation of a rainbow.

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