In the explanation of photo electric effect , we assume one photon of frequency $\alpha$ collide with an electron and transfer its energy . This leads to the equation for the maximum energy $E_{max}$ of the emitted electron as $E_{max}= h \alpha - \phi _0$ where $\phi _0$ is the work function of the metal. If an electron absorbs 2 photons (each of frequency ) what will be the maximum energy for the emitted electron ?

Question

$\begin{array}{1 1} 2 h \alpha - \phi_0 \\ h \alpha - \phi_0 \\ h \alpha -2 \phi_0 \\ 2 (h \alpha - \phi_0) \end{array}$