Definition

Noun The ratio of the speed of light in a vacuum to its speed in a specific medium. This dimensionless number quantifies how much a ray of light bends, or refracts, when it enters that material from a vacuum or air.

Usage

The term "index of refraction" is used in physics and optics to describe a fundamental optical property of transparent materials. * The index of refraction of water is approximately 1.33. * Diamonds have a very high index of refraction, which contributes to their brilliance. * To design the lens, the engineer needed to know the precise index of refraction of the glass.

Advanced Usage

• "Index of refraction" is often symbolized by the lowercase letter in equations (e.g., Snell's Law: n₁sinθ₁ = n₂sinθ₂).
• The index of refraction for a material typically varies with the wavelength of the incident light; this dependence is called dispersion.

Variants and Related Words

• Refractive Index: This is a direct synonym and is used interchangeably with "index of refraction."
• Refraction (n): The bending of a wave, such as light, when it passes from one medium into another.
• Refract (v): To cause light to change direction as a result of entering a medium with a different density.

Synonyms

• Refractive index

Related Scientific Concepts

• Snell's Law: The formula that relates the angles of incidence and refraction to the indices of refraction of the two media.
• Dispersion: The phenomenon where the index of refraction of a material depends on the light's wavelength, causing separation of colors (as in a prism).
• Critical Angle: The angle of incidence beyond which total internal reflection occurs, which is determined by the indices of refraction of the two media.

Noun

1. the ratio of the velocity of light in a vacuum to that in a medium