# Lambert's cosine law

> English word · Proper noun

## Definitions
1. A law stating that the radiant intensity or luminous intensity observed from an ideal diffusely reflecting surface or ideal diffuse radiator is directly proportional to the cosine of the angle between the direction of the incident light and the surface normal.

## Etymology
Named after Johann Heinrich Lambert.

## Source
Compiled from Wiktionary via kaikki.org (CC BY-SA). Data vintage: 2026-05-06.
Canonical page: https://plainspell.com/en/word/lambert-s-cosine-law