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  • The photoelectric threshold for some material is 200nm. The material is irradiated with radiations of wavelength 40nm. The maximum kinetic energy of the emitted photoelectron is<div class='qna-

The photoelectric threshold for some material is 200nm. The material is irradiated with radiations of wavelength 40nm. The maximum kinetic energy of the emitted photoelectron is

Option: 1

2ev


Option: 2

1ev


Option: 3

0.5ev


Option: 4

None of these


Answers (1)

best_answer

As we learned

 

Threshold Wavelength -

The maximum wave length  of incident raditaion required to eject the electron is Threshold Wavelength (\lambda_{0})

- wherein

If \lambda > \lambda _{0}  No photoelectron emission

 

 

 

work function \phi =\frac{hc}{\lambda _{0}}

\Rightarrow \phi =\frac{2\times 10^{-25}}{2\times 10^{-7}}=10^{-18}J=\frac{10^{-18}}{1.6\times 10^{-19}}ev

=6.26ev

energy of incident radiation

E=\frac{hc}{\lambda }=31.25ev

K\cdot E\cdot of photoelectron = E-\phi

                                           =25ev

Posted by

himanshu.meshram

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