Question

Find the kinetic energy of this electron as it comes out of the metal

• A. 0.46 eV
• B. 0.31 eV
• C. 0.23 eV
• D. None of these

Answer 1

The correct option is D None of these

Given : $\lambda =400$ nm $\varphi =2.2$ eV

Using $K=\frac{hc}{\lambda }-\varphi$ where $hc=1242.4$ eV

$\therefore$ $K=\frac{1242.4}{400}-2.2=3.11-2.2=0.91$ eV

Kinetic energy after two collisions $K_2={0.9}^{2}K={0.9}^2\times 0.91=0.73$ eV