826.3 The photoelectric effect 2. Experimental results and the troubles of the classical theory bright light causes an increase in current but does not cause the individual electrons to gain higher energies. The maximum kinetic energy of the electrons is independent of the intensity of the light. Classically, more intense light has larger amplitude em field and thus delivers more energy. That should not only enable a larger number of electrons to escape from the metal, it should also enable the electrons emitted to have more kinetic energy. 826.3 The photoelectric effect The maximum kinetic energy of emitted electrons does depend on the frequency of the incident radiation. Thus if the incident light is very dim but high in frequency, electrons with large kinetic energies are released. Classically, there is no explanation for a frequency dependence For a given metal, there is a threshold frequency ve. If the frequency of the incident light is below the threshold, no electrons are emitted-no matter what the intensity of the incident light. Again, classical physics has no explanation of the frequency dependence. 1010 2. Experimental results and the troubles of the classical theory ™ Bright light causes an increase in current but does not cause the individual electrons to gain higher energies. The maximum kinetic energy of the electrons is independent of the intensity of the light. Classically, more intense light has larger amplitude EM field and thus delivers more energy. That should not only enable a larger number of electrons to escape from the metal, it should also enable the electrons emitted to have more kinetic energy. §26.3 The photoelectric effect ™ The maximum kinetic energy of emitted electrons does depend on the frequency of the incident radiation. Thus, if the incident light is very dim but high in frequency, electrons with large kinetic energies are released. Classically, there is no explanation for a frequency dependence. ™ For a given metal, there is a threshold frequency νc. If the frequency of the incident light is below the threshold, no electrons are emitted—no matter what the intensity of the incident light. Again, classical physics has no explanation of the frequency dependence. §26.3 The photoelectric effect