who discovered that light travels in straight lines
Ibn al-Haytham Alhazen showed through experiment that light travels in straight lines, and carried out various experiments with lenses, mirrors, refraction, and reflection.[49] His analyses of reflection and refraction considered the vertical and horizontal components of light rays separately.[50]
Paris Peace Accords
En plein air Artists have long painted outdoors, but in the mid-19th century, working in natural light became particularly important to the Barbizon school, Hudson River School, and Impressionists.
Color Electromagnetic radiation is characterized by its wavelength (or frequency) and its intensity. When the wavelength is within the visible spectrum (the range of wavelengths humans can perceive, approximately from 390 nm to 700 nm), it is known as "visible light".