Physics

Problem

When ultraviolet light of wavelength

250\,\text{nm}

is incident on a certain metal surface, the stopping potential measured is

0.7\,\text{V}

. Assume

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

c=3\times10^{8}\,\text{m\,s}^{-1}

and

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

. a. (i) Calculate the work function

\phi

of the metal in electron-volts. b. (ii) Hence determine the threshold wavelength

\lambda_0

for this metal. c. (iii) If light of wavelength

500\,\text{nm}

is used instead, predict whether photoemission will occur. Give a quantitative justification.