Light of wavelength is incident on hydrogen atoms in the ground state

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

Problem

Light of wavelength 80 nm80\,\text{nm} is incident on hydrogen atoms in the ground state. (i) Show whether a single photon of this light has sufficient energy to ionise a ground-state hydrogen atom. (ii) If ionisation occurs, calculate the kinetic energy of the ejected electron. (iii) Determine the speed of the electron immediately after ionisation. Take h=6.63×10−34 J sh=6.63\times10^{-34}\,\text{J s}, c=3.0×108 m s−1c=3.0\times10^{8}\,\text{m s}^{-1}, me=9.1×10−31 kgm_{e}=9.1\times10^{-31}\,\text{kg} and 1 eV=1.6×10−19 J1\,\text{eV}=1.6\times10^{-19}\,\text{J}.

Related theory

Browse the problem library