The theory of photoelectricity states that when light strikes a metallic surface, it ejects electrons under certain conditions. The ejection of electrons does not happen every time a light source strikes a metallic surface but there are certain necessary conditions for the photoelectric effect to take place. The photoelectric effect is the source from which Einstein derived his definition of photons. The photoelectric effect is observed in an experiment. It was also observed that only blue and green lights can lead to the ejection of electrons. It was determined from this experiment that light waves are energy packets, which were termed photons. 

Photoelectric Effect

Photoelectrons are simply the electrons that were ejected out of the light striking a metallic surface. Threshold frequency in photoelectricity refers to the minimum frequency that is required of the incident that the light makes to emit photoelectrons. Shorter wavelengths will have higher energy. Upon a highly charged light (blue or green) hitting a metal surface and its threshold frequency will determine the expelling of photoelectrons. It is during this process that the current starts to flow. Due to the threshold frequency, the negatively charged electrons will be ejected out and travel towards the positive side. The kinetic energy of the electron is related directly to the radiation frequency.

Threshold Frequency

As discussed earlier, the threshold frequency is the frequency a light’s incident must achieve when striking a metal surface to expel electrons as photoelectrons. The kinetic energy of the electron is related directly to the radiation frequency. An increase in frequency and decrease in wavelength affects the intensity of the kinetic energy. Therefore, as understood from the above information, the threshold frequency is the minimum amount of radiation frequency required to lead to the photoelectric effect. In chemistry, students may come across to solve for the threshold frequency. 

Necessary Conditions for Photoelectric Effect

There are certain conditions under which the photoelectric effect can be observed:

• The threshold frequency has to be attained which is expressed as E = hv where E is the photon’s energy, h is Plank’s constant, and v is the frequency of photons 
• Meet or exceed the metal’s work function
• Decrease wavelength
• Increase frequency 
• Increasing intensity of light

Until and unless all of these criteria are met, the photoelectric effect will not take place. Heinrich Hertz first discovered the photoelectric effect. The relationship between electricity and light was studied in subsequent years after its discovery in 1887. In the experiment, the conditions were determined by observing it. When ultraviolet light shone on two electrodes and voltage was introduced, the light changed and there were sparks. This phenomenon was the photoelectric effect. 

Conduction of Photoelectric Effect

The conduction of the photoelectric effect is explained through experiments to answer the question of how the photoelectric effect conducts. Typically, the experiment consists of a source of light, filters that monochrome light, a vacuum tube with UV light, an electrode (E), and a collector (C) with remotely controlled voltage. 

Conclusion

One photon only interacts with one electron. It was through the discovery of the photoelectric effect that light and its properties were further clarified. The SI unit of threshold frequency is calculated in hertz. The photoelectric effect is truly significant as it proves and demonstrates particle-like characteristics of light.