Question

The work function of tungsten is 4.50 eV. Calculate the speed of the fastest electron ejected from tungsten surface when light whose photon energy is 5.80eV shines on the surface.

Answer 1

Data : Φ = 4.50 eV = 4.50 × 1.6 × 10^-19 J = 7.2 × 10^-19 J,

hv = 5.80 eV = 5.80 × 1.6 × 10^-19 J = 9.28 × 10^-19 J,

m = 9.1 × 10^-31 kg

\(\cfrac12\) mv²_max = hv - ϕ

This is the speed of the fastest electron ejected.