What is a Prism?
A prism is a transparent optical element with flat, polished surfaces that refract light. Typically made of glass or plastic, its geometric shape (often a triangular prism) is designed to split white light into its constituent spectral colors (the rainbow) through a process called dispersion.
How a Prism Works
When light enters a prism, it slows down and changes direction due to refraction. Different wavelengths (colors) of light travel at slightly different speeds within the prism material, causing them to refract at different angles. Blue light, having a shorter wavelength, bends more than red light, which has a longer wavelength, thus separating the colors.
Seeing the Rainbow: A Practical Example
A classic example of a prism's effect is passing a beam of sunlight through it to project a spectrum onto a wall. Sir Isaac Newton famously used a prism to demonstrate that white light is composed of multiple colors, and that these colors cannot be further broken down. This experiment revealed the true nature of light's composition.
Uses of Prisms
Prisms are crucial in various scientific and technological applications beyond simply producing rainbows. They are used in binoculars and periscopes to redirect light and correct image orientation, in spectrometers to analyze the spectral composition of light sources, and in some optical instruments to reflect light without absorption, serving as an alternative to mirrors.