Experimental measurements of the speed of light have been refined in progressively more accurate experiments since the seventeenth century. Recent experiments give a speed of c = 299,792,458 ± 1.2 m/s but the uncertainties in this value are chiefly those of comparisons to previous standards for the length of the meter. Therefore the above speed of light has been adopted as a standard value and the length of the meter is redefined to be consistent with this value. c ≡ 299,792,458 m/s The speed of light in a medium is related to the electric and magnetic properties of the medium, and the speed of light in vacuum can be expressed as In vacuum, all electromagnetic waves travel at c, the speed of light. he speed of light c is said to be the speed limit of the universe because nothing can be accelerated to the speed of light with respect to you. A common way of describing this situation is to say that as an object approaches the speed of light, its mass increases and more force ...
Optics for Optometry