11.8 Light of frequency is incident on a metal surface

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

Problem

11.8 Light of frequency

7.21 \times 10^{14} \mathrm{~Hz}

is incident on a metal surface. Electrons with a maximum speed of

6.0 \times 10^{5} \mathrm{~m} / \mathrm{s}

are ejected from the surface. What is the threshold frequency for photoemission of electrons?