What is the primary physical reason why primary rainbow formation exhibits violet light on the inner edge and red light on the outer edge?

💡 Solution & Explanation

When white sunlight enters a spherical raindrop, it undergoes refraction, internal reflection, and refraction upon exit. The refractive index of water varies slightly with wavelength, a phenomenon known as dispersion, where shorter wavelengths like violet bend more than longer wavelengths like red. Consequently, red light emerges at an angle of approximately forty-two degrees while violet emerges at forty degrees, placing red on the outer rim and violet on the inner rim of the primary bow. Distractors incorrectly attribute this to absorption or diffraction rather than differential refractive deviation. Secondary rainbows exhibit reversed color sequences due to undergoing two internal reflections.