# Threshold Frequency, Threshold Wavelength, Work Function and Stopping Potential

## 1)Threshold Frequency

Threshold frequency is the minimum frequency of incident radiation on the metal surface below which photoelectrons emitted from the surface.It’s value is fixed for fixed metal surface but varies from one to another metal.

The energy of photon carrying corresponding to threshold frequency (Î½0) is

E =hf0

where f0 = Threshold Frequency

## 2) Threshold wavelength

When maximum value of wavelength of incident radiation,which when incident on the metallic surface does not emits the electrons from the surface is called threshold wavelength.

In the another word, The wavelenth corresponding to the threshold frequency of radiation is called threshold wavelength. it is denoted by lamda not and measure in the unit meter.

The energy of radiation corresponding to the threshold wavelength is

E =hf0

E = hc/lamda not

where lamda not = threshold wavelength

c = speed of light

h = planck’s constant

## 3) Work Function

Work function of metal or non-metal is defined as the minimum energy absorbed by the surface to eject in electron without impacting any K.E of photoelectron. work function of materials depends upon it’s nature.Generally alkali metals of lithium, Sodium,Potassium having comparatively low work function.so, this matal prefer to make photocells.

work function of surface is measured in the joule unit or electron volt .

we have,

1eV = 1.6 * 10^-19 J

The function of surface is equal to the energy of photon corresponding to the threshold frequency .

i.e Î¦ = hÎ½0

## 4)Stopping potential

The minimum value of retaring potential by the application of which in the metallic surface .The ejection of photoelectron become just stop is called stopping potential.

It is measure in Volt and denoted by( Î½0).

Here, the work done by retiring potential is equivalent to the kinetic energy gained by electron.

W = K.E

eV0 = 1/2mv2

V0 = v2/[2(e/m)]

Question

1)What is Stopping potential?

â€¢ The minimum value of retaring potential by the application of which in the metallic surface .The ejection of photoelectron become just stop is called stopping potential.

2)What is Threshold frequency?

â€¢ Threshold frequency is the minimum frequency of incident radiation on the metal surface below which photoelectrons emitted from the surface.

3) what is work function?

â€¢ Work function of metal or non-metal is defined as the minimum energy absorbed by the surface to eject in electron without impacting any K.E of photoelectron.

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