Concept Quiz

Einstein's Photoelectric Equation

Albert Einstein explained this effect by treating light as discrete particles (photons). An electron is only ejected if a single photon's energy exceeds the metal's specific Work Function ($\Phi$).

$$ E_{photon} = \Phi + KE_{max} $$ $$ h\nu = h\nu_0 + \frac{1}{2}m_e v^2 $$
$E_{photon}$ = Energy of incident photon ($hc/\lambda$)
$\Phi$ = Work Function (Minimum binding energy of the metal)
$KE_{max}$ = Maximum Kinetic Energy of ejected electron
$\nu_0$ = Threshold Frequency (Minimum frequency to eject electron)

Note: Visual representation is a pedagogical model. Photon/electron speeds and sizes are scaled for visual clarity.