Photoelectrons are emitted when radiation is incident on a surface of work function

PHYSICS · Subjective · CBSE · Physics · Atoms · Atoms

Problem

Photoelectrons are emitted when

400\,\mathrm{nm}

radiation is incident on a surface of work function

1.9\,\mathrm{eV}

. These photoelectrons pass through a region containing

\alpha

-particles. A maximum-energy electron combines with an

\alpha

-particle to form a

\mathrm{He^+}

ion, emitting a single photon. The

\mathrm{He^+}

ions thus formed are in their fourth excited state. Find the energies, in eV, of photons in the

2

4\,\mathrm{eV}

range that are likely to be emitted during and after combination. Take

h=4.14\times10^{-15}\,\mathrm{eV\,s}