Electromagnetic waves are emitted when charged particles lose energy e.g. when fast moving electrons are stopped by collision in an X-ray tube, slow down or change direction or an electron in an atom moves to a shell of lower energy.The EM radiation is emitted in short bursts or packets called photons.Each burst leaves the atom in a different direction. A photon from electromagnetic radiation directed at the surface of a metal can be absorbed by an electron. The electron is emitted from the surface of the metal. This is called the photoelectric effect.The energy E of a single photon is given by:
h = Planck constant 6.63×10-34 Js.A laser beam consists of photons of the same frequency. The power of the laser beam is given by:Power = nhfwhere n is the number of photons passing a fixed point every second.
E = h f
f = frequency Hzh = Planck constant 6.63×10-34 Js.A laser beam consists of photons of the same frequency. The power of the laser beam is given by:Power = nhfwhere n is the number of photons passing a fixed point every second.