* Light is part of the electromagnetic spectrum, the spectrum is the collection of all waves, which include visible light, Microwaves, radio waves ( AM, FM, SW ), X-Rays, and Gamma Rays.
* In the late 1600s, important questions were raised, asking if light is made up of particles, or is it waves .? * Sir Isaac Newton, held the theory that light was made up of tiny particles. In 1678, Dutch physicist, Christian Huygens, believed that light was made up of waves vibrating up and down perpendicular to the direction of the light travels, and therefore formulated a way of visualising wave propagation. * This became known as ‘Huygens’ Principle’. Huygens theory was the successful theory of light wave motion in three dimensions. Huygen, suggested that light wave peaks form surfaces like the layers of an onion. In a vacuum, or other uniform mediums, the light waves are spherical, and these wave surfaces advance or spread out as they travel at the speed of light.
* In 1803, Thomas Young studied the interference of light waves by shining light through a screen with two slits equally separated, the light emerging from the two slits, spread out according to Huygen’s principle. Eventually the two wave fronts will overlap with each other, if a screen was placed at the point of the overlapping waves, you would see the production of light and dark areas * Later in 1815, Augustin Fresnel supported Young’s experiments with mathematical calculations. * In 1900 Max Planck proposed the existence of a light quantum, a finite packet of energy which depends on the frequency and velocity of the radiation.
* In 1905 Albert Einstein had proposed a solution to the problem of observations made on the behaviour of light having characteristics of both wave and particle theory. From work of Plank on emission of light from hot bodies, Einstein suggested that light is composed of tiny particles called photons, and each photon has energy. * Light theory branches in to the physics of quantum mechanics, which was conceptualised in the twentieth century. Quantum mechanics deals with behaviour of nature on the atomic scale or smaller. * As a result of quantum mechanics, this gave the proof of the dual nature of light and therefore not a contradiction.
MODELS OF LIGHT
Light is a very complex system to model perfectly, which is why you see very few computer generated images that look photo-realistic. As is always the case, the more complex and realistic your simulation is, the more computation you will have to do, and thus the slower it will run. As a programmer, you have to decide what payoffs you are willing to make, whether you want your program to look amazing, and thus take an hour to render a single image, or to run at 60 frames per second and look like a cartoon.
Light consists of tiny packets of energy called photons. A photon is both a particle and a wave, meaning that it can exhibit wave behaviour or particle behaviour as it pleases. These packets are emitted from an energy source, and travel in straight lines until they interact with an object. Light can also be totally weird and spooky if it feels like it.
A photon can do one of several things when it hits an object. * Reflection: The photon bounces off the object. * Absorption: The photon is absorbed, and gives the object it’s energy. * Refraction: The photon travels through the object and changes direction depending on the properties of the object and it’s surroundings. * Diffraction: If the photon just misses the object, or passes between two objects which are very close together, it can change direction.
* RAY MODEL – The simplest mode of light. * WAVE MODEL – Color is naturally described in terms of wavelength. Required in order to explain the interaction of light with material objects of sizes comparable to or smaller than a wavelength of light. * PARTICLE MODEL – Required in order to explain the interaction of light with individual atoms. At the atomic level, it becomes apparent that the beam of light has a certain graininess to it.
SPEED OF LIGHT
The speed of light in vacuum, commonly denoted c, is a universal physical constant important in many areas of physics. Its value is 299,792,458 metres per second, a figure that is exact because the length of the metre is defined from this constant and the international standard for time.
PROPAGATION OF LIGHT
* Light and similar forms of radiation are made up of moving electric and magnetic forces. A simple example of motion similar to these radiation waves can be made by dropping a pebble into a pool of water. * The up-and-down motion is transverse, or at right angles, to the outward motion of the waves. This type of wave motion is called transverse-wave motion. The transverse waves spread out in expanding circles until they reach the edge of the pool. * Light radiates from its source in all directions until it is absorbed or diverted by some substance.