The Human Eye and the Colourful World

Violet

Step 1: When white light enters a prism, it gets dispersed into its component colors due to different refractive indices. Step 2: Each color has a different wavelength - violet has the shortest wavelength and red has the longest. Step 3: The refractive index of glass is higher for shorter wavelengths (violet) and lower for longer wavelengths (red). Step 4: According to Snell's law, higher refractive index means greater bending of light rays. Step 5: Therefore, violet light bends the most and red light bends the least when passing through a prism. This is why violet appears at one end of the sp

VIBGYOR

Step 1: When white light is dispersed by a prism, it forms a spectrum of seven colors. Step 2: The colors appear in order of their wavelengths, from shortest to longest. Step 3: Starting from the most bent (shortest wavelength): Violet, Indigo, Blue, Green, Yellow, Orange, Red. Step 4: The acronym VIBGYOR helps remember this sequence easily. Step 5: This sequence is always the same because it follows the natural order of wavelengths in the electromagnetic spectrum. ROYGBIV would be the reverse order, which is incorrect for the standard spectrum display.

White light is recombined

Step 1: The first prism disperses white light into its seven component colors (VIBGYOR). Step 2: When these dispersed colors enter the second inverted prism, each color refracts again. Step 3: The second prism bends each color in the opposite direction compared to the first prism. Step 4: Since the prisms are identical and inverted, the second prism exactly reverses the dispersion of the first. Step 5: All the colors recombine to form white light again, proving that white light is made up of seven colors. This famous experiment by Newton demonstrated the composition of white light.

Dispersion of sunlight by water droplets

Step 1: A rainbow forms when sunlight encounters tiny water droplets suspended in the atmosphere after rain. Step 2: Each water droplet acts like a tiny prism, dispersing the white sunlight into its component colors. Step 3: The sunlight undergoes refraction when entering the droplet, then total internal reflection at the back surface. Step 4: Finally, the light refracts again while exiting the droplet, with each color bending at slightly different angles. Step 5: This dispersion process separates white light into VIBGYOR colors, creating the rainbow arc we see in the sky opposite to the sun's