Class 12 Physics Dual Nature Radiation Matter Result of the Experimental Study of Photoelectric Effect

## Result of the Experimental Study of Photoelectric Effect

• Photoelectric current is directly proportional to the intensity of incident light
• Saturation current increases if intensity of radiation increases
• Stopping potential doesn’t depend on the intensity of light

• Sopping potential, and maximum kinetic energy of photoelectrons, are linearly related to the frequency of incident light
• For every material, there is a minimum value of frequency (threshold frequency) of incident light required for photoelectric emission to take place, below which no photoelectric effect occurs

• Photoelectric emission is an instantaneous process, meaning there is no time lag between the incident light and the emission of free electrons (photoelectrons).

Exercise:

In an experiment of photoelectric effect, the intensity () was doubled. Find the change in the following:a) Photoelectric current (i), b) Stopping potential (Vo), and c) maximum kinetic (Kmax) energy of the photoelectrons.

Solution:

a) From the experiments on photoelectric effect, we know that :  i is directly propertion to I. So, photoelectric current gets doubled.

b) We know that stopping potential doesn’t depend on the intensity. So, stopping potential remains unchanged

c) We also know that maximum kinetic energy, doesn’t change with intensity. So, maximum kinetic energy remains unchanged

Exercise:

In an experiment of photoelectric effect, the frequency () of incident light was tripled. Find the change in the following: a) Saturation current (i), and b) work function of metal.

Solution:

a) Saturation current is independent of frequency. So, saturation current remains unchanged.

b) Work function is always fixed for a given material.

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