Photons of sunlight that have wavelength while traveling through air enter a swimming…
PHYSICS · Multi-part · A Level · Physics · Particles and radiation · Particles and radiation
Problem
Photons of sunlight that have wavelength 550nm while traveling through air enter a swimming pool whose water has an index of refraction nw=1.33. Assume the photons are incident normally on the water surface and that dispersion is negligible over the wavelength range considered.
(a) Calculate the wavelength of one of these photons while it is inside the water.
(b) Determine the momentum of the photon while it is in air and while it is in water.
(c) Compute the energy of the photon in both media and comment on any difference or lack thereof. Explain how your result is consistent with relevant conservation laws.
(d) Estimate how many such photons must be absorbed by a black surface at the bottom of the pool to deliver 1.0mJ of energy.