Question

What is the formula to find the speed of light?

Answer 1

Hint: The speed of light is a universal and fundamental constant that expresses the speed by which light travels in space. Here, when we say space, we generally mean vacuum and atmosphere. We will first see the methods by which speed of light was calculated and see the modern formula to find the speed of light.

Complete step-by-step solution:
When we say the speed of light, we quickly jump to the conclusion that its speed is $3\times {10}^{8}m{s}^{-1}$ , but the fact that it earlier estimated to be infinity is quite astonishing.
In the late 1600s, a Danish astronomer Ole Roemer became the first person to calculate the speed of light. He calculated the speed of light by timing eclipses of Jupiter’s moon Lo. His works were later used by Huygens to give a rough idea of the speed of light. Huygens calculated the speed of light to be 131,000 miles per second whereas the actual speed of light is 186,000 miles per second.
Also, in Modern Physics, the formula of speed of light can be given by:
$\Rightarrow c=\lambda f$
Here,
‘c’ is the speed of light.
‘$\lambda$’ is the wavelength of light. And,
‘f’ is the frequency per second.
Under appropriate scientific observations and calculations, the absolute speed of light is calculated to be:
$\Rightarrow c=299,792,458m{s}^{-1}$
Hence, the formula used to calculate the speed of light is, $c=\lambda f$.

Note: Since, light is an electromagnetic radiation whose wavelength lies in the visible spectrum, its speed is used as a base to estimate the speed of other electromagnetic radiations like the absolute speed of gamma rays, X-rays, microwaves, radio waves, etc.