Classical model of light.... NB - let us consider light as a purely classical electromagnetic phenominum - no mention of quantum. ( The reason for this is that is feel that it is important i have an indepth undertanding of the classical theory of light, which will therefore allow me to see more clearly where the probablems which led to the development of quantum theory arose. ) In classical wave theory, we treat light (and the rest of the EM spectrum) as if it results from an electric (and therefore magnetic) field, which imposes a force on other charged objects. However, in order to account for the formation of a wave, we say that this field takes time to “travel”; this speed being 3*10^8 m/s. Eg – Suppose we take an electron which is oscillating up and down, and a proton which is responding to that. ( NB : for the sake of simplification we shall say that the proton can ONLY move up and down; it can not accelerate towards the elctron.) This would therefore produe a situation like the one found through the link below, with the proton on a slight time delay to the motion of the elctron, as it must wait for the change in the field to reach it. http://www.colorado.edu/physics/2000/waves_particles/wavpart4.html Now, effectively what we have here is a light ray travelling between the 2 particles. Ie – an oscillating electric field wave. The energy possessed by this wave is dependant upon its amplitude. ( ie – its intensity.) However, this amplitude becomes smaller and therefore weaker as the wave permeates through space, since the strength of an electric field is inversely proportional to the distance from the source squared. However, any charged particle in the path of the light will still be pushed up and down in pperiodic motion; just to a lesser extent. My questions arise from what people apparently thought the results of the photoelectric effect should have been, before they knew anything about quantum. According to the AS text book, if we used the wave model then we would suppose that “waves gradually transfer energy to all the elctrons near metal saurface. Eventually a large number of electrons gain enough energy to leave the metal.” Now, obviously this is not what is observed, but my question is in fact on how this should ties in with classical wave theory. How can the waves gradually transfer energy to the electrons? All a light ray is is an electric (and therefore magnetic) field which will cause an electron to periodically oscillate “in time” with the wave – how does this electron gain energy from this? Does the light’s amplitude in fact decrease as it interferes with the electron, which absorbs energy as it passes through it meaning the light amplitude is not just dependant on distance, or at least something along those lines? Also, if a charged particle continues to gain more and more energy as light is shown on it, does it oscillate with an increasing amplitude compared to the set amplitude of the light? WHy do charged particles not moved faster and faster and more wildely therefore when exposed to othermoving charged particles around them? (because surely this effectively the same thing? ) Thanks in advance.