The momentum p associated with a photon can be calculated using the equation:
$\mathit{p}=\frac{\mathit{E}}{\mathit{c}}$
where E is the energy of the photon and c is the speed of light in a vacuum.
Given that the energy E of the photon is 1.5 eV, and the speed of light c is approximately $3\times {10}^8$ meters per second, we can calculate the momentum p:
$\mathit{p}=\frac{1.5\mathrm{}\mathit{e}\mathit{V}}{\mathit{c}}$
$\mathit{p}\approx 1.5\times 1.6\times \frac{{10}^{-19}}{\mathit{J}}3\times {10}^8\mathrm{}\mathit{m}∕\mathit{s}$
$\mathit{p}\approx 2.4\times \frac{{10}^{-19}}{\mathit{J}}3\times {10}^8\mathrm{}\mathit{m}∕\mathit{s}$
$\mathit{p}\approx 8\times {10}^{-28}\mathrm{}\mathit{k}\mathit{g}\mathrm{}\mathit{m}∕\mathit{s}$