Speed of Light

Light travels very fast. IN fact, light traveling in vacuum is the fastest moving thing in the
universe. Scientists have not discovered anything faster than light traveling in vacuum.
According to physical laws there is nothing that is faster than light. Maxwell’s law shows that the
speed of light in a vacuum is constant. Therefore, irrespective of who measures it, the velocity
of light will always be same.

What then is the speed of light? The speed of light is roughly 3×108 m/s. Usually, the symbol v is
used to represent the velocity of an object. However, for light, the symbol c is used instead
because it is a universal constant. C is an abbreviation of the Latin word celeritas, which means
swift. The equation for the velocity of light is
c = fλ, where f is frequency, λ is wavelength of the light.

Even though the velocity of light is really high, it is not infinite. So it takes light certain amount of
time to travel from place to place. For example, it takes 8 minutes and 18 seconds for light from
Sun to reach Earth. A light reflected off Moon takes about 1.3 seconds to reach Earth. The light
from the star that is closes to the solar system takes about 4 years to reach Earth.

One unique feature of light is that it does not require a medium to travel. Unlike sound and water
waves, light can traverse in vacuum.