A metal surface has a work function $\varphi =2.7,\text{eV}$. Light of wavelength $400,\text{nm}$ is shone on it. Which of the following is the maximum kinetic energy of the emitted electrons?

Step-by-step solution

1. Calculate photon energy: $E=hc/\lambda =1240,\text{eV,nm}/400,\text{nm}=3.10,\text{eV}$,
2. Apply Einstein’s photoelectric equation: $K_{max}=E-\varphi =3.10-2.70=0.40,\text{eV}$
3. Select the option that matches $0.40,\text{eV}$

Concept tested: Einstein photoelectric equation

Published 1 October 2026 · How this solution was prepared and checked