. The index of refraction is the ratio of the speed of light .

in a material to the density of the material

in the material to the speed of light in a vacuum

in a vacuum to the speed of light in the material

in a vacuum to the speed of light in the material

Explanation:

The index of refraction, also known as the refractive index, is the ratio of the speed of light in a vacuum to the speed of light in the material.

When light rays travel travels from one medium to another, it bends as a result of a change in the speed of traveling from the first medium to the second medium.

The refractive index (n) of a material is calculated by:

                     sin i/sin r

Where i = the incidence angle of the traveling ray in the vacuum and r = angle of refraction.

The refractive index (n) is also given as:

                         c/v

Where c = velocity of light in the vacuum and v = velocity of light in the material.

the answer is tropical areas. the tropical areas obtain more

radiant energy from the sun than they lose to space through terrestrial

radiation, and vice versa for polar areas. earth has an energy remaining in the

tropics and an energy scarcity for the polar areas.

explanation:

energy and particles