wever, this was not the case forphotoelectricity, in which the electrons are freedinstantly. The Electromagnetic Theory sustains thatlight waves carry energy whether they are of highor low frequency. Therefore, the frequency of lightshould not be a factor in the emitting of electrons.Once, again the photoelectric effect contradictsthe Wave Theory. In the photoelectric effect onlyhigh frequency light can cause electrons to beemitted no matter how long the light is shined. Thephotoelectric effect was a major roadblock in theway of total acceptance of the Wave Theory ofLight. Einstein’s Theory In 1905, Albert Einsteinpublished a revolutionary theory that explained thephotoelectric effect. According to Einstein, lightand other forms of radiation consist of discretebundles of energy which were later given the term‘photons’. The energy contained in each photondepends on the frequency of the light in which theyare found. The energy of the emittedphotoelectron can be determined using theequation E = hf, where h is Plank’s constant,6.626 x 10 –34 J/Hz. According to Einstein’stheory an electron is ejected from the metal by acollision with a single photon in the process, all thephoton energy is transferred to the electron andthe photon ceases to exist. However, the result isthe creation of a photoelectron. Since electronsare held together in a metal by attractive forces,some minimum energy Wo (work function) isrequired to release an electron from the bindingforce. If the frequency (f) of the incoming lightcauses hf to be less than Wo, then the photons willnot have enough energy to emit any electrons.However, if hf is greater than Wo, then theelectrons will be liberated and the excess energybecomes the kinetic energy of the photoelectron,allowing it to travel, creating an electric current.Einstein’s theory uses the existence of a thresholdfrequency to explain the photoelectric effect. Aphoton with minimum e...
