A researcher directs a laser beam of wavelength 532 nm in vacuum through a block of…
PHYSICS · Multi-part · A Level · Physics · Particles and radiation · Particles and radiation
Problem
A researcher directs a laser beam of wavelength 532 nm in vacuum through a block of fused silica (refractive index n=1.50 for this wavelength). Inside the block, photons travel more slowly than in vacuum.
Use the following constants as needed:
• speed of light in vacuum: 3.00×108ms−1
• Planck constant: 6.626×10−34Js
(a) Calculate the speed of the photons while they are inside the fused-silica block.
(b) Determine the frequency of the photons within the block.
(c) Compute the energy, in joules, of a single photon that is propagating through the fused silica.
(d) State whether the energy of an individual photon changes when it enters the fused-silica block from vacuum, and justify your answer using physical principles.