An electromagnetic wave of wavelength in vacuum emerges from a laser and sequentially…
PHYSICS · Multi-part · CBSE · Physics · Light — Reflection and Refraction · Light — Reflection and Refraction
Problem
An electromagnetic wave of wavelength 520nm in vacuum emerges from a laser and sequentially passes through two transparent blocks before reaching a detector.
• Block X is fused silica in which light travels at 2.04×108ms−1.
• Block Y is water in which light travels at 2.25×108ms−1.
The wave is incident normal to every interface. After leaving block Y it enters air where its speed is 3.00×108ms−1.
(a) Determine the wavelength of the light while it is inside block X.
(b) Using the result from part (a), calculate the wavelength of the same light while it is inside block Y.
(c) Rank the four wavelengths of the light—in vacuum before block X, inside block X, inside block Y, and in air after block Y—from greatest to least. Provide a brief justification for your ranking.
(d) Immediately after exiting block Y, the light passes through a linear polarizing filter whose transmission axis makes an angle of 60∘ with the electric-field oscillations of the incident beam. Describe qualitatively how the detected intensity compares with the intensity just before the filter, and explain the underlying physical principle.