The photoelectric effect is a widely known phenomenon in the realms of science particularly notable for its contribution to understanding the properties of light. It was discovered by Friedrich Hertz, then it was studied by Philipp Lenard and Max Planck. It was through the scientific breakthrough made by Einstein that the debate around light’s characteristics was finally resolved. The light had wave-like behaviour but travelled through space as particles called photons in packets of energy. This fundamentally changed our understanding of what light is and how it behaves. The study of the photoelectric effect is relevant in subjects stretching from astrophysics to materials science. 

Characteristics of Photoelectric Effect

In the photoelectric effect, a monochromatic light is exposed to a body. When its wavelength is short enough or has a frequency above the threshold frequency, then electrons are emitted when that light is absorbed. The characteristics of photoelectric effect have three primary things to note: there is no lag time, there is a cut-off frequency and the kinetic energy of the photoelectrons is independent. These characteristics of photoelectric effect were observed over some time through various experiments with the photoelectric effect on different materials. The Work Function is also an important element involved in the study of the characteristics of the photoelectric effect. The work function is essentially the energy required to start the emission of electrons from the surface of a metal. It is represented by an ∅. 

Photoelectric Effect Explanation of Characteristics

The lag time characteristic implies that when the light strikes the material of the electrode electrons is instantaneously released. This characteristic is observed even at very low radiation incident intensities which is a contradiction to classical physics. The intensity of radiation and photoelectrons’ kinetic energy when plotted on graphs can represent this characteristic of the photoelectric effect. In the case of positive potential difference, the current rises until it plateaus. Beyond this point, no photocurrent increases. Higher intensity gives higher photocurrent. In the case of negative potential, with the absolute potential difference increasing, photocurrent decreases and is 0 at the stopping point. The physical property of the material determines the cut-off frequency. This is the point after which photocurrent stops occurring. The cut-off frequency is the minimum frequency of the surface of the material. 

Impact of Material on Photoelectric Effect

The threshold frequency varies with the material. This simply means that the work function and the frequency of the metal (material) that determines the cut-off frequency together influence the photoelectric effect. For example, the following has been provided for better understanding:

• Na (Sodium) has a work function of 2.46
• Zn (Zinc) has the work function of 4.31
• Pt (Platinum) has the work function of 6.35
• Fe (Iron) has the work function of 4.50

Stopping Potential

The stopping potential is the minimum amount of negative voltage that is required for an anode to stop the photocurrent. The applied voltage is equal to the maximum kinetic energy when it is measured in volts. In the case of negative potential, with the absolute potential difference increasing, photocurrent decreases and is 0 at the stopping point.

Conclusion

The Photoelectric effects are reproducible in a laboratory’s setup. The striking of radiant light onto a surface of a material with enough energy and frequency displaces and emits electrons as photoelectrons. The setup usually consists of a cathode, anode, an emitter and collector, and a source of light. This light used can either be ultraviolet light, infrared or gamma rays.