Question

Find the maximum potential a $Cu$ ball (isolated) can have when irradiated with a wavelength $\lambda =140$ $nm$.
$[{\varphi }_{Cu}=4.47$eV]

• A. 4.47 $V$
• B. 8.86 $V$
• C. 13.33 $V$
• D. 4.39 $V$

Answer 1

The correct option is D 4.39 $V$

We have
$E=e{V}_s=(\frac{hc}{\lambda }-\varphi )J$

$⟹V_s=(\frac{1240}{\lambda }-\varphi )eV$

$⟹E=\frac{1240}{140\times {10}^{-9}}-4.47=8.86-4.47=4.39eV$

So, the answer is option (D).