Q3DQ - University Physics with Modern Physics

Question

A beam of light goes from one material into another. On physical grounds, explain why the wavelength changes but the frequency and period do not.

Step-by-Step Solution

Answer

Wavelength changes as the waves lose some of their energy while the frequency and the period are the same as the exerted force.

Step 1: Definition of Wavelength

Wavelength is the distance between two successive peaks.

Step 2: Description of why the wavelength changes when a beam of light goes from one material into another

The electric and magnetic fields oscillate with a certain frequency and on the boundary surface between the materials, they start interacting with the molecules of the material they enter. The force acting on the molecules has the same period as the period of the oscillating fields entering the material so at the stationary regiment, everything will oscillate with that frequency and period. The speed of propagation of waves has to change since they lose some of their energy on moving the molecules of the material and thus wavelength also changes. 

Thus, wavelength changes because the waves lose some of their energy on moving the molecules of the material.