5.0 Photoelectric Effect

  Basic Modern Physics

• When light of appropriate frequency (or sufficiently small wavelength) is incident on a metal surface,electrons are ejected from the metal. This phenomenon is known as photoelectric effect and the ejected electrons are called as photoelectrons.

• For this to happen energy of incident photon($E$) $ \geqslant $ work function of the metal ($W$).$$\begin{equation} \begin{aligned} E \geqslant W \\ hf \geqslant W \\ f \geqslant \frac{W}{h} \\\end{aligned} \end{equation} $$$$\begin{equation} \begin{aligned} {f_0} = \frac{W}{h} \\ \downarrow \\ (Threshold\ Frequency) \\\end{aligned} \end{equation} $$$$\begin{equation} \begin{aligned} {\lambda _0} = \frac{{hc}}{W} \\ \downarrow \\ (Threshold\ Wavelength) \\\end{aligned} \end{equation} $$ where ${f_0}$ is the minimum frequency for photoelectric effect to occur and ${\lambda _0}$ is the maximum wavelength for photoelectric effect to occur.