Speed of light in vacuum, air, glass

From AnchorQuantitiesExercise

Speed of light in vacuum, air, glass
Speed of Light in a Vacuum: 299,792,458 meters per second [source]
Speed of Light in Air: 298,925,574 meters per second [source]
Speed of Light in Glass: ~ 2x10^8 meters per second [source]

Details/Sources
Mnemonic to aid in remembering: (count the letters in each word)
'We Guarantee Certainty, Clearly Referring To This Light Mnemonic' [source]

Other Notes:
c comes from the Latin word celeritas meaning "swiftness"

The speed of light remains the same in different media but it is delayed. This delay is captured by the index of refraction of the different media which is the ratio of the speed of light in the relevant medium to the speed of light in a vacuum. It's also easier to find the refractive index online than it is to find the speed of light through a medium.

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