(a(i))[2]
Show that a photon of electromagnetic radiation with wavelength $\lambda$ has momentum $p = \frac{h}{\lambda}$, where $h$ is the Planck constant.
(a(ii))[1]
Use the result in (a)(i) to show that a photon in free space with momentum $9.5 \times 10^{-28}\,\text{N s}$ is red light.
(b(i))[2]
Show that the rate at which photons strike the mirror is $1.4 \times 10^{15}\,\text{s}^{-1}$.
(b(ii))[3]
Use the data in (b)(i) to find the pressure produced by the light beam on the mirror.
(c)[2]
The red-light beam in (b) is now swapped for a blue-light beam with the same intensity. Suggest and explain whether the pressure on the mirror from the blue beam is less than, the same as, or greater than the pressure from the red beam.