The work function for the following metals is given $Ni: 5.15 \; ev$ What happen if the laser is brought never and placed 50 cm away ?

Question

$\begin{array}{1 1} \text{Emission increases in Na and K } \\ \text{Emission increases in Mo and Ni } \\ \text{Emission increases in all the metals } \\ \text{Emission increases only in Na } \end{array}$