Light, the Quantum Concept, and the Photoelectric Effect

The physics governing light has laid the foundation for the quantum mechanical model of the atom. This modern model of the atom uses the principles uncovered by Planck and Einstein to further explain the nature and behavior of electrons in atoms. Light travels in waves, and it is possible to measure both the wavelength and frequency of a photon based on the fact that all light travels at the same speed, known as the speed of light. While the speed of light is constant for all light, the wavelength and frequency vary dramatically. As the wavelength increases, the frequency decreases and vice versa. This classic inverse relationship provides a very simple algebraic formula for calculating wavelength or frequency. The quantity of energy that light has depends on the wavelength and frequency of the light. This relationship is quantized. That means that light does not exist in a continuous amount of energy, but rather specific packets of energy called quanta. The energy of light is always some multiple of Planck’s constant.