When sunlight (white light) falls on a triangular glass prism, a band of colours called a spectrum is obtained. Which one among the following represents this effect appropriately?

When white light passes through a triangular glass prism, it splits into its constituent seven-color components, a phenomenon known as dispersion [1]. This effect occurs because different colors of light travel at different speeds within the glass medium, causing each wavelength to have a unique refractive index. Consequently, each color bends through a different angle relative to the incident ray; red light bends the least, while violet light bends the most [1]. While the underlying mechanism is refraction (the bending of light as it changes media), the specific process of separating white light into a band of colors or a spectrum is termed dispersion [1]. Isaac Newton first demonstrated this using a glass prism to show that white light is a mixture of distinct colors [2].

Sources

1. [1] Science , class X (NCERT 2025 ed.) > Chapter 10: The Human Eye and the Colourful World > Activity 10.2 > p. 167
2. [2] https://en.wikipedia.org/wiki/Dispersive_prism