The work function of copper is

PHYSICS · Subjective · A Level · Physics · Particles and radiation · Particles and radiation

Problem

4.5\,\text{eV}

. Find the stopping potential required to just stop the most energetic electrons when the surface is illuminated with ultraviolet light of wavelength

200\,\text{nm}

. (

h=6.63\times10^{-34}\,\text{J\,s}

c=3.0\times10^{8}\,\text{m\,s}^{-1}

e=1.6\times10^{-19}\,\text{C}

)