Some Glimpse Of Photoelectric Effect

 

Photoelectric Effect:

The phenomenon of emission of electron from a metal surface by the incidence of electromagnetic radiation of appropriate frequency is called photoelectric effect.

                 The emitted electron by this process is called photo electron. Electron is not emitted from the metal surface for any radiation. For different types of metal electrons are started to emit by different minimum frequency, this minimum frequency is called threshold frequency and the wavelength associated with this frequency is called threshold wavelength.

Work Function:

In the metal free electrons are vibrate about their equilibrium position or moves around various direction for thermal excitation. Free electrons are hit metal surface diagonally. So, their kinetic energy is not sufficient to come out from the metal surface. In this situation electrons are able to escape or come out from the metal surface if some energy is supplied externally.

Therefore, the minimum energy which is require for an electron to come out from a particular metal surface is called the work function of that metal. usually denoted as Φ.

Now, considering ʋ₀ as the threshold frequency the work function is generally hʋ₀.

Stopping Potential:

The flow of electron in photoelectric tube or current in the external circuit becomes zero for which minimum negative potential is called stopping potential.

Important Observation about Photoelectric Effect:

1.       Emission of electrons is not depended on the intensity of light but on the frequency.

2.       For the change in amounts of photoelectrons, photoelectric current also change.

3.       Bright light yields more photoelectrons than a dim one of same frequency.

4.       Energy of photoelectrons depends on the frequency of radiation. The higher the frequency of radiation the more energy have the photoelectrons. So, the blue light causes the faster photoelectrons than red light.