A surface has light of wavelength `lamda_1=550nm` incident on it, causeing the ejection of photoelectrons for which the shopping potential is `V_(s1)=0.19V`. If the radiation of wavelength `lamda_2=190nm` is now incident on the surface, (a) calculate the stopping potential `V_(s2)`, (b) the work function of the surface, and (c) the threshold frequency for the surface.

A surface has light of wavelength `lamda_1=550nm` incident on it, caus

1.	A surface has light of wavelength `lamda_1=550nm` incident on it, causeing the ejection of photoelectrons for which the shopping potential is `V_(s1)=0.19V`. If the radiation of wavelength `lamda_2=190nm` is now incident on the surface, (a) calculate the stopping potential `V_(s2)`, (b) the work function of the surface, and (c) the threshold frequency for the surface.
Answer» For the first wavelength : `eV_(s1)=hupsilon-W` ...(i) `W=`work function: `eV_(s1)=hupsilon_2-W` ...(ii) Subtracting, we get `V_(S2)-V_(S1)=(h)/(e)(upsilon_2-upsilon_1)` or `V_(S2)=V_(S1)+(hc)/(e)((1)/(lamda_2)-(1)/(lamda_1))` `V_(S1)+(hc)/(e)((lamda_1-lamda_2)/(lamda_1lamda_2))` `=0.19+1240((550-190)/(190xx550))=4.47V` b. From Eq. (i): `W=(hc)/(lamda_1)-eV_(S1)` Work function (in eV) `(W)/(e)=(hc)/(elamda_1)-V_(S1)=(1240)/(550)-0.19=2.07eV` c. Threshold frequency: `V_0=(W)/(h)=(2.07xx1.6xx10^(-19))/(6.62xx10^(-34))=5xx10^(14)Hz`

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