In a perfect vacuum, light waves travel at 300,000 kilometers every second. when light waves travel through materials, such as air, they a. speed up b. slow down c. increase in amplitude d. heat up

c = speed of light in vacuum = 300,000 kilometers/second

n = index of refraction of material

v = speed of light in the material

Speed of light in a given material is given as

v = C/n

v = 300,000/n

for air, the value of index of refraction "n" is slightly greater, hence the speed of light in air is smaller than 300,000 kilometers/second. hence the light waves slow down.

so correct choice is

B.slow down

the arctic is a region of the planet, north of the arctic circle, and includes the arctic ocean, greenland, baffin island, other smaller northern islands, and the far northern parts of europe, russia (siberia), alaska and canada.

im sorry i dont know