Ultraviolet light of wavelength strikes a metal surface

PHYSICS · Single correct · A Level · Physics · Particles and radiation · Particles and radiation

Problem

Ultraviolet light of wavelength

250\,\text{nm}

strikes a metal surface. The fastest electrons are observed to have a speed of

8.0\times10^{5}\,\text{m/s}

. What is the work function of the metal? Use

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

c=3.00\times10^{8}\,\text{m/s}

m_e=9.11\times10^{-31}\,\text{kg}

, and

1\,\text{eV}=1.60\times10^{-19}\,\text{J}

. (a)

4.96\,\text{eV}

(b)

1.3\,\text{eV}

(c)

3.1\,\text{eV}

(d)

6.8\,\text{eV}