In glass index of refraction is 15 thus 18600015 124000 miles per second. Refractive index of the water is 133 and for glycerin is 1473. Since 1983 speed of light is 299792458 meters per second because a meter was defined as 1299792458 light-seconds in that year.
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1 Unlock answers. The SI derived unit for speed is the metersecond. Light travels at 30 108 ms in a vacuum. 1 metersecond is equal to 86400000 millimeter per day or 44364024692431E-9 speed of light water.