Physics Dual nature

Question

If the energy of a photon incident on a metal is equal to the work function of the metal, What will be the Kinetic energy of the electron emitted from the metal ?

Answer 1

If the energy of a photon incident on a metal is equal to the work function of the metal, 

Then, the kinetic energy of the emitted electron will be zero.

 This is because the photon energy is just enough to overcome the work function, allowing the electron to be emitted but not providing any additional energy for kinetic motion. Thus, the kinetic energy (KE) can be expressed as:

KE=E_photon−ϕ\text{KE} = E_{\text{_photon}} - \phiKE=Ephoton−ϕ

where E_{photonE_}{\text{_photon}}Ephoton is the energy of the photon and ϕ\phiϕ is the work function. If E_photon=ϕE_{\text{_photon}} = \phiEphoton​=ϕ, then:

KE=0\text{KE} = 0

KE=0