<p align="right">Last Update: <font color="#4f81bd">July, 16, 2024</font></p> ## BIG IDEAS - All light travels at a speed of 3 x 10⁸ m/s. - This speed is based on light traveling in a vacuum. - Light can slow down based on the mediums such as water, glass, or air (refractive properties) - All light are transverse waves (and can behave as particles called [[Photon|photons]]) - Light carries [[Energy|energy]] from one place to another - Light obeys the [[Wave Equation|wave equation]]. - Light can be absorbed or emitted by an object. ### Background - The study of light is called **optics**. - The father of optics is Alhazen (Ibn al-Haytham, 950-1040) even though Euclid (325 – 265 BCE) authored work on optics using geometry (lines or rays). - Descartes suggested that colors arise during light’s passage through a medium. - [[Notes Vault/Physics Notes Vault/Physicists/Classical Physics/Isaac Newton|Isaac Newton]] described light as composed of particles in his 1672 paper on the refraction of light through a prism. He stated that sunlight contains light rays of different colors. He did this by reversing the reasoning used by his contemporaries; that is, <span style="background:#d3f8b6">he suggested color is a basic property that can be used to explain white light</span>. - [[Robert Hooke]] explained light in terms of vibrations (like Descartes) but stated color is a distortion of the pulse rather than the medium. ### Production of Light - Light (electromagnetic radiation) is produced during an oscillating electric and magnetic field. - The interaction of the two fields is perpendicular to each other. - At the atomic level, quanta of light are produced when electrons in excited atoms move to lower energy levels in the atom. - The excess energy is given off as photons (packets of light). --- Return [[Home|Home]] | [[Oscillations]] | [[Electromagnetic radiation]] | [[Module 5 Electromagnetic Spectrum]] | [[Wave Equation]] | [[Module 2 Light Reflection]] | [[Module 2 Light Reflection]]