Physics 9702 · AS & A Level · Energy and momentum of a photon
Energy and momentum of a photon — practice question
A beam of light of wavelength $590\,\text{nm}$ falls normally on a surface, as shown in Fig. 8.1. Its power is $3.2\,\text{mW}$. The surface absorbs all of the light.
(a)[3]
Calculate the number of photons reaching the surface in $1.0\,\text{s}$.
(b(i))[3]
Use your answer in (a) to find the total momentum of the photons striking the surface in $1.0\,\text{s}$.
(b(ii))[1]
Use your answer in (a) to determine the force exerted on the surface by the light.
Worked solution & mark scheme
This 7-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Applies $E = \dfrac{hc}{\lambda}$” …