The work function for the following metals is given: Na:2.75eV,K:2.30eV,Mo:4.17eV,Ni:5.15eV. Which of these metals will not give photoelectric emission for a radiation of wavelength 3300 Å from a He-Cd laser placed 1 m away from the photocell ? What happens if the laser is brought nearer and placed 50 cm away ?

The work function for the following metals is given: Na:2.75eV,K:2.30

1.	The work function for the following metals is given: Na:2.75eV,K:2.30eV,Mo:4.17eV,Ni:5.15eV. Which of these metals will not give photoelectric emission for a radiation of wavelength 3300 Å from a He-Cd laser placed 1 m away from the photocell ? What happens if the laser is brought nearer and placed 50 cm away ?
Answer» <html><body><p></p>Solution :Here `lamda=3300Å=3300xx10^(-10)m=3.3xx10^(-17)m` <br/> `therefore`Energy of radiation photon in eV <br/> `E=(hc)/(elamda) eV=(6.63xx10^(-34)x3xx10^(8))/(1.6xx10^(-19)xx3.3xx10^(-7))eV=3.767eV` <br/> For photoelectric emission energy of radiation photon must be greater than or equal to the work function of given metal. therefore, we conclude that in present <a href="https://interviewquestions.tuteehub.com/tag/case-910082" style="font-weight:bold;" target="_blank" title="Click to know more about CASE">CASE</a> photoelectric emission from <a href="https://interviewquestions.tuteehub.com/tag/na-572417" style="font-weight:bold;" target="_blank" title="Click to know more about NA">NA</a> and K is possible but from Mo and Ni no photoelectric emission will take place. <br/> There is no effect on photoelectric emission from Mo and Ni even when laser source is brought nearer to the <a href="https://interviewquestions.tuteehub.com/tag/photocell-1153412" style="font-weight:bold;" target="_blank" title="Click to know more about PHOTOCELL">PHOTOCELL</a>. <a href="https://interviewquestions.tuteehub.com/tag/however-1032379" style="font-weight:bold;" target="_blank" title="Click to know more about HOWEVER">HOWEVER</a>, on bringing the source nearer, the intensity of radiation increases. As a result, in case of Na and K, the value of photoelectric current will rise in proportion to the rise in intensity of radiation.</body></html>

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