Explanation:

The phenomenon of the formation of rainbows is a result of the refraction, reflection, and dispersion of light as it passes through water droplets in the atmosphere. When sunlight enters a raindrop, it undergoes refraction, which causes the light to change direction and separate into its component colors. This separation of colors is known as dispersion.

Primary Rainbow:
The primary rainbow is formed when sunlight enters a raindrop, undergoes refraction, and then reflects off the inner surface of the water droplet. The light wave is partially reflected and partially refracted again as it exits the droplet. The different colors of light are dispersed and spread out, forming a circular band of colors with red on the outer edge and violet on the inner edge.

Secondary Rainbow:
The secondary rainbow is formed by a second internal reflection within the raindrop. As the light wave exits the droplet after the first internal reflection, it undergoes another refraction and reflects off the outer surface of the droplet before exiting. This second reflection causes the light to undergo an additional 180-degree phase shift, resulting in a reversal of the sequence of colors.

Explanation of the Reverse Sequence:
When the light wave undergoes the second reflection, the colors of light are once again dispersed and spread out. However, the order of the colors is reversed compared to the primary rainbow. This reversal occurs because the second reflection causes the light to undergo an additional 180-degree phase shift.

The reversal of the sequence of colors in the secondary rainbow can be further understood by considering the path of a light wave as it undergoes reflection and refraction within the raindrop. The light wave enters the droplet, undergoes refraction, reflects off the inner surface, undergoes refraction again, reflects off the outer surface, and finally exits the droplet. Each reflection and refraction causes a phase shift in the light wave, resulting in the reversal of the colors.

In conclusion, the sequence of colors in the secondary rainbow is reversed compared to the primary rainbow due to the second internal reflection and the resulting 180-degree phase shift of the light wave.