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

It decreases

Explanation:

The speed of light in a vacuum is

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

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:

Water:

Glass:

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

Air:

Water:

Glass:

electromagnetic shielding is the practice of reducing the electromagnetic field in a space by blocking the field with barriers made of conductive or magnetic materials. shielding is typically applied to enclosures to isolate electrical devices from their surroundings, and to cables to isolate wires from the environment through which the cable runs. electromagnetic shielding that blocks radio frequency electromagnetic radiation is also known as rf shielding.

the shielding can reduce the coupling of radio waves, electromagnetic fields and electrostatic fields. a conductive enclosure used to block electrostatic fields is also known as a faraday cage. the amount of reduction depends very much upon the material used, its thickness, the size of the shielded volume and the frequency of the fields of interest and the size, shape and orientation of apertures in a shield to an incident electromagnetic

from wikipedia