Photoelectric current is a specific type of current produced through the process of the photoelectric effect. The photoelectric effect can be defined as the process in which electron ejection occurs from the metal surface when light falls on it. The electrons that are ejected are known as photoelectrons. It should be noted that the photoelectron emission and the KE of the photoelectron that has been ejected are dependent on the light’s frequency that is incident on the metal surface. The process in which photoelectrons are mostly emitted from the metal surface through the action of light is known as photoemission. 

Photoelectric current and history of the photoelectric effect

Wilhelm Ludwig Franz Hallwachs first introduced the photoelectric effect in 1887. Heinrich Rudolf Hertz did the experimental verification of the experiment. Together they found that when a metal surface is exposed to electromagnetic radiation of a higher threshold of frequency, the metal surface absorbers this radiation and emits electrons. In current times, the photoelectric effect is studied as a phenomenon of a metal that absorbs electromagnetic radiation and in turn, releases particles that are electrical charges. More precisely, light falling on the metal surface makes the electrons excited and so they are ejected. The electron that is ejected as a result of the photoelectric effect is a photoelectron. This photoelectron is usually denoted by e-. As a result of this ejected photoelectron, a current is produced. This current is called photoelectric current.

Photoelectric effect characteristics and factors affecting it

Photoelectric effect and thereby photoelectric current have several characteristics. Firstly, it is important to remember that the threshold frequency of each particular material is different. Hence threshold frequency of each material should be studied before discussing its photoelectric effect on it. Next, it should be remembered that photoelectric current is directly proportional to the intensity of light. Thirdly, the photoelectron’s kinetic energy varies directly with the frequency of the light. Lastly, the potential of stopping varies directly with the frequency and for this reason, the process is instantaneous. 

In this context, the factors that affect incident radiation can also be mentioned. The photoelectric current and hence photoelectric effect is dependent on three main factors. Firstly, the photoelectric effect is dependent on incident radiation intensity. Secondly, It also depends on the incident radiation frequency. Lastly, the photoelectric current depends on the difference between the collector and the metal plate.

Application of photoelectric current

There are several practical applications of the photoelectric effect and photoelectric current. These have been identified in the following.

• It can be observed that smartphones use light sensors that enable the user to have automatic screen brightness adjustment. This occurs as a result of the photoelectric current generated being directly dependent on the light intensity that hits the sensor.
• Photoelectric current is also used for generating electricity with solar panels. In solar panels, metal combinations are present that help in electricity generation through a variety of wavelengths. 
• Digital cameras are equipped for detecting as well as recording light. This occurs due to photoelectric sensors present in them that are equipped for responding to light’s different colors. 
• Position and motion sensors: Here, the particular photoelectric material is present in the front of IR LED or UV. When a particular object is kept in front of a LED as well as a sensor and the light source is cut from the source, a potential difference change can be noticed. 
• Photoelectric cells channeling photoelectric current are placed within burglar alarms. 
• Photoelectric current is also seen to be used in photomultipliers for the detection of low levels of light. 

Conclusion

The overall article has been carried out as a simple guide to photoelectric current. Photoelectric current is defined as the process in which electrons are emitted from a metal surface when light falls over it. The concept of photoelectric current is very important in chemistry and is a vital topic for the UPSC exam. Throughout the article, the concept of photoelectric current has been further discussed by analyzing the history of the photoelectric effect. In addition, the characteristics of the photoelectric effect and the factors that affect it have also been discussed. Lastly, some practical applications of photoelectric current have been identified.