Question

Suppose light travels 1.5 times faster in a vacuum than it does in glass. What is the index of refraction for glass?

Answer 1

1.5

Explanation:

Refractive index is the ratio of the speed of light in a vacuum to the speed of light in a given medium. In this case that is the ratio of the speed of light in a vacuum to the speed of light in a particular glass.

Interestingly, the higher the refractive index of a substance, the more "sparkle" or "fire" an object will show. While regular glass has a refractive index of 1.5, lead crystal can have an index of refraction of 1.7 to 1.8. It sure does look pretty in direct sunlight!

Sapphire has a refractive index of 1.77 and diamond has a refractive index of 2.42. Moissanite (gem-quality silicon carbide) has a refractive index of 2.65.

All that sparkles generally has a high refractive index!