What is the primary reason why primary rainbows exhibit a violet inner edge and a red outer edge, whereas secondary rainbows show the reverse order?

💡 Solution & Explanation

Primary rainbows are formed when sunlight undergoes two refractions and a single total internal reflection inside water droplets, resulting in red appearing on the outer rim and violet on the inner rim. Secondary rainbows occur when sunlight undergoes two refractions and two internal reflections, which inverts the color sequence so that violet appears on the outer edge and red on the inner edge. Secondary rainbows are fainter because extra internal reflection causes significant light loss.