Photoelectric Effect Simulation

The photon energy is given by \( E = hf \), where \( h \) is Planck's constant and \( f \) is the frequency of light.

When a photon strikes a metal surface, it can eject an electron if the photon energy exceeds the work function \( \phi \) of the metal:

The maximum kinetic energy of the ejected electrons is: \( KE_{\max} = hf - \phi \)

Below the threshold frequency \( f_0 = \phi / h \), no electrons are emitted regardless of the light intensity. This cannot be explained by the wave model of light.

Evidence for light quanta: The photoelectric effect demonstrates that light energy is quantised — it arrives in discrete packets (photons) of energy \( E = hf \).

Wave model failure 1: The wave model predicts that any frequency of light, given sufficient intensity, should eject electrons. In reality, there is a sharp threshold frequency below which no emission occurs.

Wave model failure 2: The wave model predicts a time delay before emission as energy accumulates. In reality, emission is instantaneous even at very low intensities.

Intensity effect: Increasing intensity increases the number of photons (hence the photocurrent), but does NOT increase the maximum kinetic energy of individual electrons — only increasing frequency does that.

Particle nature: The photoelectric effect is key evidence for the particle nature of light, complementing the wave evidence from diffraction and interference.