Themes > Science > Physics > Quantum Physics > Quantum theory of light > Wave-Particle Duality > Expectations of Classical Physics

These expectations are based on the belief that light is an electromagnetic wave; if we increase the intensity of the light this is equivalent to increasing the amplitude of the oscillating electric field of which the light wave is composed. Since the energy of the light beam is spread uniformly over the beam, it is transferred continuously to the electrons, which require a certain minimum of energy to escape the attractive forces of the metal. In the following, "The maximum energy of the electrons" means "The energy of the most energetic electrons".
    a. Whatever the frequency of the incident light, electrons will be emitted from the metal surface as long as the light carries enough energy - i.e. if it is sufficiently intense.

    b. If the intensity of the light is increased the maximum energy of the electrons should also increase.

    c. There may be a time delay between the switching on of the light and the appearance of the first electrons; the lower the light intensity, the longer will be this time delay.


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