An electromagnetic wave of wavelength in return, moves. In this part we consider the photon model of the electromagnetic wave. We note n the density of photon (number of photons per cubic meters - unit : 1/m³). We consider the case where the photons strike the plate with the angle 0 = 0° with respect to the normal to the surface and are then totally reflected (Figure 1). = 630 nm exerts a force on a plate of surface S which Plate Figure 1 1/ Show that the photon density n can be written as : n = 2hc where Em is the amplitude of the electromagnetic wave. Hint : Use the energy of one photon, the density of photon n and the energy density of an electromagnetic wave.

An electromagnetic wave of wavelength in return, moves. In this part we consider the photon model of the electromagnetic wave. We note n the density of photon (number of photons per cubic meters - unit : 1/m³). We consider the case where the photons strike the plate with the angle 0 = 0° with respect to the normal to the surface and are then totally reflected (Figure 1). = 630 nm exerts a force on a plate of surface S which Plate Figure 1 1/ Show that the photon density n can be written as : n = 2hc where Em is the amplitude of the electromagnetic wave. Hint : Use the energy of one photon, the density of photon n and the energy density of an electromagnetic wave.