How does light behave like a particle?

malarson

This is demonstrated by the photoelectric effect. Light is shined on a piece of metal, causing electrons to be ejected. Classical theory said that E of ejected electron should increase with increase in light intensity---not observed. No ejected electrons are observed until light of high enough frequency. Number of electrons ejected depends on light intensity. This is also from my chemistry notes, but it doesn't make near as much sense as why light behaves like waves. It is important to note that electromagnetic radiation is composed of neither waves nor particles. Oct 18 06, 8:53 PM

Diamondlance

Photons--"light particles"--have also been shown to have momentum. A 1923 experiment by Arthur Compton involving X-ray photons colliding with carbon. These photons were shown to eject electrons from the carbon target, thus giving them momentum, and the wavelength of the scattered X-rays is shifted up, indicating a loss of energy to the ejected electrons. This could probably be found in any text dealing with modern physics, but I specifically used "Fundamentals of Physics" 7/E by Halliday, Resnick and Walker. Oct 19 06, 12:38 AM

What-A-Mess

"In modern physics, the photon is the elementary particle responsible for electromagnetic phenomena. Photons are emitted in many natural processes, e.g., when a charge is accelerated, when an atom or a nucleus jumps from a higher to lower energy level, or when a particle and its antiparticle are annihilated." Light is made up of particles. http://en.wikipedia.org/wiki/Photon http://en.wikipedia.org/wiki/Photon Oct 19 06, 12:42 AM

danarothrock

"Number of electrons ejected depends on light intensity." No, the number of electrons ejected depends on the intra-atomic quanta of binding energy holding the electrons in the shell. This is like heating water in a kettle. Steam is not produced until the water is heated to 212 F at STP when the kinetic energy of the water molecules exceeds VanDerWaals force. Steam is not produced because of some quantum affect of heat "particles" (also electromagnetic energy as waves). I have never bought the particle theories. Oct 01 12, 5:17 PM