SPEED OF LIGHT (C)

The speed of an electromagnetic wave in free space , precisely 299,792,458 m/s. Note 1: The preceding figure is precise because by international agreement the meter is now defined in terms of the speed of light . Note 2: The speed of an electromagnetic wave, e.g. , light, is equal to the product of the wavelength and the frequency . Note 3: In any physical medium , the speed of light is lower than in free space. Since the frequency is not changed, the wavelength is also decreased. [After FAA ]