Why does a light ray travel slower through a glass block?

Answer 1

When light enters certain materials like glass or water it is absorbed by the atoms and molecules in the material as energy. These energized atoms and molecules then give up their energy by emitting light. The whole process is actually very complicated but the absorption and reemittance process effectively slows the progress of the light thru the material.

Answer 2

It slows down because the speed of electromagnetic radiation is determined by the electrical characteristics of the material it's traveling through, specifically, the electrostatic permittivity and the magnetic permeability. Those numbers are different for every material. The speed of light in the material is 1/(the square root of their product). It's slower in any material than it is in vacuum.

Answer 3

Because the molecules of glass are more conjusted so, light travels slow in glass.

The molecules of air are spread in the atmosphere so, light has a wide way to travel in the air. They are two mediums (air and glass), their speed of light vary.

Answer 4

The photons of light interact with the atoms (particularly the electrons) in the glass, the combined effect of these interactions is to slow the effective progress of the light.

that is because glass is denser than air which causes a refraction or the bending of a straight line of light

Answer 5

What is meant by the term, speed of light?

Unless stated otherwise, the term "speed of light" is understood to mean the speed of light in a vacuum. Light travels slower through other mediums, such as air, glass and water. This happens because light is absorbed and re-radiated by the atoms that make up the medium. And it’s not just light that we’re concerned with. All electromagnetic radiation, which includes radio, microwave, infrared, light and X-rays travel at the speed of light.

The history of speed of light measurements

To see why the confidence in the invariance of the speed of light is so high, we need to look at the history of its measurement, and some of the foundations that lead to the development of Albert Einstein’s theory of special relativity. The first attempt to measure the speed of light that was successful was made by Olaus Roemer in the late 1600s. He timed the differences in the orbital motions of the moons of Jupiter from when Jupiter and the Earth are relatively close compared to when they are far apart. Based on his measurements, the speed of light was calculated to be 2.3 x 108meters/second (m/s). (Jones, Childers 1990a:613). Not bad given the uncertainties of the size of earth’s orbit at that time.

In 1849, Louis Fizeau performed the first experiment on the Earth to measure the speed of light. His apparatus consisted of a toothed wheel, a source of light, and an arrangement of lenses and mirrors that allowed light to move along a path, be reflected from a mirror and through the toothed wheel and back. The toothed wheel was set to rotating, and light’s passage through the teeth could be matched to the wheel’s speed. Fizeau’s calculations yielded a value of 3.15 x 108m/s for the speed of light. (Jones, Childers 1990b:613).

After Fizeau established this method, others have used it or a similar method involving light reflecting off a rotating mirror to make ever more accurate measurements. Other methods have also been devised. They include using Kerr Cells, which chop light up similar to the toothed wheel but are controlled electronically, geodimeters which used modulated light for measuring distances and were mainly used for geologic work, and microwaves and lasers, where measurements based on their frequency, wavelength and phase relationships were made. Below is a table of some selected measurements made over the years. (Halliday, Resnick 1978:925; Halliday, Resnick 1988:543; Monchalin, 1977)

Answer 6

It slows down (due to its particle property), because glass is a thicker medium.

Answer 7

There are more particals packed closer together for the light to pass through

Answer 8

light t ravels with different speed in different medium since the glass is thicker than air light will slow down