NESA Physics Light: Quantum Model

Incorrect. The energy supplied by the incident photon is represented by the term $hf$, not $\phi$.

Incorrect. The energy retained by the electron as kinetic energy after being ejected is represented by $K_{\text{max}}$.

Correct. The symbol $\phi$ represents the work function, which is the minimum energy required to overcome the attractive forces and release an electron from the material.

Incorrect. The energy left over after freeing the electron becomes its maximum kinetic energy, represented by $K_{\text{max}}$.

Einstein's model states that light consists of photons with energy inversely proportional to wavelength ($E = hc/\lambda$). Electrons are only ejected if a single photon has enough energy to overcome the metal's work function, which requires the light to have a wavelength shorter than a specific threshold.

In the photon model, increasing light intensity increases the number of photons (and thus the number of ejected electrons), but it does not change the energy of individual photons or the maximum kinetic energy of the electrons.

The maximum kinetic energy of ejected electrons depends on the metal's work function ($K_{max} = hf - \Phi$), which is a property that varies depending on the specific type of metal used.

According to the photon model, if the light's wavelength is above the threshold, no electrons will be emitted regardless of how long the metal is exposed to the light, because individual photons lack the energy to eject an electron.