Photoelectric effect

• The photoelectric effect involves light and electrons, and is the main piece of evidence for the quantum theory of light.
• Isaac Newton was the first person to come up with a quantum theory of light when he thought that light travelled in little packets called core puzzles but he thought that they had mass.
• Huygens or if you want to pronounce it properly it's a ho Hunt's came along instead and proposed that light acts like a wave and we see that way of diffraction.
• The energy of one photon is equal to H F F being the frequency of the light and HB in Planck's constant a six point six three times 10 to the minus 34 joule-seconds.
• Einstein and people after him did experiments with light and electrons to prove that light comes in discrete packets of energy, which are called photons.
• If a piece of metal is illuminated with light, electrons are liberated from the surface of the metal.
• As the frequency of light increases, more electrons are liberated, and their kinetic energy increases.
• One photon is absorbed by one electron, meaning you can't have two photons being absorbed by the same electron and therefore having twice the energy.
• Electrons can be liberated from the surface of a metal, and their kinetic energy is determined by the maximum possible kinetic energy to jump a gap.
• The photoelectric effect proved that higher intensity, which is more photons, does not increase the kinetic energy of the electrons.
• The maximum kinetic energy of electrons liberated from the surface of a metal is determined by the frequency of light.
• When the frequency of light is very low, no electrons are liberated.
• The energy needed to liberate an electron is known as the work function of a metal.
• The work function of a metal is different for every type of metal.
• Light exists as quanta, meaning it exists in tiny little bits of energy known as photons.
• The threshold frequency is the frequency at which electrons start being liberated.
• The kinetic energy of these electrons is measured by setting up an evacuated tube and shining light on a plate, with a current being set up in the circuit when electrons are liberated.
• The voltage applied to the circuit is increased until no electrons reach the other side, at which point the stopping potential is measured.
• The stopping potential is the potential required to stop the electrons jumping the gap.
• The kinetic energy of an individual electron can be calculated by doing the charge of an electron times the stopping potential.