Physics - Modern Physics Question with Solution | TestHub

${\mathrm{KE}}_{\max }=(5-\mathrm{\varphi })\mathrm{eV}$

when these electrons are accelerated through $5\text{V}$ , they will reach the anode with maximum energy $=(5 -\mathrm{\varphi } + 5)\mathrm{eV}$

$$\begin{gathered} 10 - \mathrm{\varphi } = 8 \\ \mathrm{\varphi } = 2\mathrm{eV} \end{gathered}$$

Current is less than saturation current because if slowest electron also reached the plate it would have $5 \mathrm{eV}$ energy at the anode, but there it is given that the minimum energy is $6 \mathrm{eV}$.