Physics Question from my Lab???

Question

Explain how Quantum Mechanics differs from Classical Mechanics. How does this difference apply in the photoelectric effect?

Answer 1

In classical mechanics, the energy of light would in part be transferred to kinetic energy of the emitted electrons. From this, one would expect that a more intense light would yield more energetic electrons, and that the wavelength of light shouldn't matter. However, from the quantum mechanical viewpoint, the energy of the emitted electrons depends only on the wavelength, and the intensity only governs the number of electrons emitted. In addition, classical mechanics implies a linear relation between input energy and electron energy, but what actually happens is that below a certain input energy (light frequency), no electrons are emitted; after that, energy is linear with frequency.