Light in air and vacuum travels at a speed of 300,000 km / s. The speed of light depends on the medium in which the light travels. So, in sugar, the speed of light is 192,300 km / s, in diamond – 124,100 km / s, rock salt – 194,300 km / s, in milk – 222,200 km / s, in gasoline – 214,300 km / s (speeds lights are given at a body temperature of 20 ° C.
Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.