What is the Photoelectric effect?
Important equations for this topic
\(e=hf\)
\(hf=\phi+E_{k (max)}\)
The Photoelectric Effect
- If you shine radiation of a high enough frequency onto the surface of a metal, then it will instantly emit electrons called photoelectrons. This frequency required is usually in the ultraviolet wavelength.
- This is not cumulative.
The 4 conclusions
- No matter how much radiation you fire, you will never get an electron if the frequency is not high enough.
- The photoelectrons are emitted with various kinetic energies. Some have 0 kinetic energy, and some have the maximum kinetic energy.
- The intensity of the radiation is the amount of energy hitting an area of the metal per second. The maximum kinetic energy of the photoelectrons is unaffected by varying the intensity of the radiation.
- The number of photoelectrons emitted per second is proportional to the intensity of the radiation.
Summary
- The Photoelectric Effect is the phenomenon in which electrons are emitted from the surface of a metal when it is exposed to light.
- This effect is only observed when the frequency of the light is above a certain threshold, known as the threshold frequency.
- The kinetic energy of the emitted electrons is directly proportional to the frequency of the light, and is independent of the intensity of the light.
- The Photoelectric Effect is important because it was the first experimental evidence to support the idea that light can behave as both a wave and a particle, known as the wave-particle duality.