Factors affecting Photoelectric Effect

Photoelectric effects refer to a process in which an electron escapes the atom after receiving the sufficient amount of energy it wants. The electrons that find their way out of the atom are known as photoelectrons. The equation given by Albert Einstein on the photoelectric effect is:

EK = h*f – ∅. Here, EK refers to the highest kinetic energy of the electron which pops-out= universal constant, f refers to a light’s frequency abanet refers refers to the work function. 

It is proved that the rays of light should be high because an electron needs to get a high amount of energy before making its way out of the atom to become photoelectrons. If the ray of light is low then the electrons may not be able to make their way out of the atom. Many important factors affect photoelectric effects. 

Factors Affecting Photoelectric Effects

The 3 factors affecting photoelectric effects are:

• Effects of the intensity of incident radiation on photoelectric effects:
• Effects of potential difference between metal plate and collector on photoelectric effects
• Effect of frequency on photoelectric effects

Effects of Intensity of Incident Radiation on Photoelectric Effects

The capable gap between the plate is made up of metal, collector, and frequency of the light which is kept fixed and the light’s intensity will not be fixed it varies. The electron C changes to positive by seeing the metal plate which is D. It is said that the rate at which the photoelectrons get out from the atom is directly proportionate to the power of the incident radiation. 

Effects Of Potential Difference Between Metal Plate and Collector On Photoelectric Effects

The density of the light and the power is always kept fixed and the capable difference that lies between the metal plates is not constant it varies. As the power and the density of the light falling are kept fixed then the potential C which is positive generally increases. The photoelectrons which are emitted out of the atom are at varying velocities and the highest is in the process at which they are on the surface of the metal. 

Effects Of Frequency on Photoelectric Effects

The power of the light is kept fixed and the density of the light which falls varies. For having a constant power of the light, the difference in the density of the light in turn leads to the production of a linear variation which leads to the stoppage of the metal. The surface which gets cut off is directly proportionate to the density of the incident radiation. 

These were the important factors affecting photoelectric effects. 

Practical Questions on Photoelectric Effects

As we know that the factors affecting photoelectric effects are very important and they lead to the formation of many practical questions which are:

The work function of potassium is 2.30 eV. UV light of wavelength 3000 Å and intensity 2 Wm-2 is incident on the potassium surface. i) Determine the maximum kinetic energy of the photoelectrons ii) If 40% of incident photons produce photoelectrons, how many electrons are emitted per second if the area of the potassium surface is 2 cm2?

The energy of the photon is

E = hc/λ

 = 6.626×10−34 × 3×108 / 3000×10−10

E = 6.626×10−19 J = 4.14 eV

Maximum KE of the photoelectrons is

Kmax = hv – ϕ0 = 4.14 – 2.30 = 1.84 eV

1. ii) The number of photons reaching the surface per second is

np = P/E × A

 = [2 / 6.626×10−19] × [2×10−4]

 = 6.04×1014 photons / sec

The rate of emission of photoelectrons is

= (0.40) np = 0.4×6.04×1014

= 2.415´1014 photoelectrons / sec.

Conclusion

The factors that affect photoelectric effects are the intensity of incident radiation, the potential difference between the metal plate and collector, and the frequency of photoelectric effects. They affect the photoelectric effects and thus restrictthem. Photoelectric effects refer to the light that falls on the metal surface which creates the energy and induces the electrons to come out of the atom from the surface of the metal which are also called photoelectrons.