Question

Based on the images seen here, identify which phase of matter would transmit light waves the fastest, and why?
Responses
A The gas would transmit the fastest because the particles move the fastest.The gas would transmit the fastest because the particles move the fastest.
B The solid would transmit the fastest because the particles are closest together.The solid would transmit the fastest because the particles are closest together.
C The liquid would transmit the fastest because the particles are the most freely moving.The liquid would transmit the fastest because the particles are the most freely moving.
D The gas would transmit the fastest because there are the fewest particles to interfere with the waves.

Answer 1

D.

Gases transmit light fastest because they have the lowest particle density (closest to vacuum), so the light interacts and polarizes the medium less and the refractive index is nearer 1. That lower optical density means a higher light speed. (Particle thermal motion does not determine the light speed.)