Dispersion of white light through a prism occurs because different colors of light refract (bend) at different angles when passing through the prism, due to their varying wavelengths. This phenomenon separates white light into its constituent colors, creating a visible spectrum. The ray diagram illustrates this by showing how each colored ray, when entering the prism, deviates (bends) at a different angle depending on its wavelength.
Explanation and Ray Diagram:
1. Incident White Light:
White light is a combination of all the colors of the visible spectrum (red, orange, yellow, green, blue, indigo, and violet).
2. Refraction at the First Surface:
When the white light enters the prism, it refracts (bends) at the first surface because it’s entering a denser medium (glass) from a less dense medium (air). Different wavelengths (colors) of light bend at slightly different angles due to varying refractive indices for different colors within the prism. Violet light, with the shortest wavelength, bends the most, while red light, with the longest wavelength, bends the least.
3. Refraction at the Second Surface:
The refracted light then strikes the second surface of the prism and refracts again as it exits back into the less dense medium (air). This second refraction further separates the colors, and they emerge from the prism as distinct bands of colors.
4. Visible Spectrum:
The emerging rays of different colors create the visible spectrum, with red on top (bends least) and violet at the bottom (bends most). The order of colors is red, orange, yellow, green, blue, indigo, and violet (ROYGBIV).