Question

How is the speed of light affected when it passes through air, water, or glass ?​

Answer 1

It decreases

Step-by-step explanation:

The speed of light in a vacuum is

`c=3.0\cdot 10^8 m/s`

When it travels into a medium, however, light slows down. the speed of light in a medium is given by the equation

`v=(c)/(n)`

where

v is the speed of light in the medium

c is the speed of light in a vacuum

n is the refractive index of the medium

We see that the larger the refractive index of the medium, the lower the speed of light in that medium. For air, water and glass we have:

Air:
`n=1.000277`

Water:
`n=1.33`

Glass:
`n=1.52`

So we can calculate the speed of light in the three mediums:

Air:
`v=(3.0\cdot 10^8 m/s)/(1.000277)\sim 3.0\cdot 10^8 m/s`

Water:
`v=(3.0\cdot 10^8 m/s)/(1.33)\sim 2.26\cdot 10^8 m/s`

Glass:
`v=(3.0\cdot 10^8 m/s)/(1.52)\sim 1.97\cdot 10^8 m/s`