The photoelectric effect is the experimental result that got Albert Einstein his Nobel Prize, so I thought it would be interesting to check out. It provides proof for the quantization of light.
When you shine a light on a metal, electrons are emitted from it. So, to explain this with classical physics, physicists said that as light is just a wave (in classical physics), it can exchange any amount of energy with the metal. What they thought was that the stronger the intensity of light they shine at a metal, the higher the kinetic energy of the electrons released. This was because they thought that when the light is beamed on the metal, the electrons in the metal absorb the light and gather up enough energy to leave the atom. But this wasn’t the case. Electrons were emitted as soon as the light was shone at the metal. No matter how weak.
However, varying frequency of light did show a difference. The higher the frequency, the higher the kinetic energy of the electrons emitted. But only after a certain threshold. If you shine a light below the threshold frequency, then no electrons were emitted.
The electrons come from a pool of free electrons in the metal (the outer shell) and in order for them to be released, they need to be provide equivalent energy to the metal’s work function (the amount of energy required for an electron to leave a metal in a solid state into a vacuum).
This was hard to explain in classical physics so enter Einstein. Inspired by Max Planck’s quanta, he concluded that light was quantized (like oscillators) into tiny bosons called photons. Light acted like particles as well as waves. So, when the energy of the photon is greater than the work function of the metal, the electron is emitted.
However, varying frequency of light did show a difference. The higher the frequency, the higher the kinetic energy of the electrons emitted. But only after a certain threshold. If you shine a light below the threshold frequency, then no electrons were emitted.
The electrons come from a pool of free electrons in the metal (the outer shell) and in order for them to be released, they need to be provide equivalent energy to the metal’s work function (the amount of energy required for an electron to leave a metal in a solid state into a vacuum).
This was hard to explain in classical physics so enter Einstein. Inspired by Max Planck’s quanta, he concluded that light was quantized (like oscillators) into tiny bosons called photons. Light acted like particles as well as waves. So, when the energy of the photon is greater than the work function of the metal, the electron is emitted.
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