# Sodium and copper have work function 2.3 eve and 4.5 ev. Then the ratio of the wavelength is nearest to

We know that$\dpi{80} W_0=h\nu=\dfrac{hc}{\lambda}$
Hence$\dpi{80} W_0\propto \dfrac{1}{\lambda}$
$\dpi{80} \implies \dfrac{\lambda_1}{\lambda_2}=\dfrac{4.5}{2.3}=1.96$