Photoemission of electrons occurs from a metal ( φ_0=1 · 96 eV ) when light of frequency 6.4 × 10^14 Hz is incident on it. Calculate: (a) Energy of a…

Energy of a photon in the incident light:

E = hν = ($\displaystyle 6.626$ × $\displaystyle 10$⁻³⁴ × $\displaystyle 6.4$ × $\displaystyle 10$¹⁴) / ($\displaystyle 1.6$ × $\displaystyle 10$⁻¹⁹) = $\displaystyle 2.64$ eV (= $\displaystyle 42.24$ × $\displaystyle 10$⁻²⁰ J)

Maximum kinetic energy:

K_max = E − φ₀ = $\displaystyle 2.64$ − $\displaystyle 1.96$ = $\displaystyle 0.68$ eV (= $\displaystyle 10.88$ × $\displaystyle 10$⁻²⁰ J)

Stopping potential:

eV₀ = K_max ⟹ V₀ = K_max / e = $\displaystyle 0.68$ V.