Question

What is the velocity of all electromagnetic waves in a vacuum?

Answer 1

Answer:

$c=3\cdot 10^8 m/s$

Explanation:

All electromagnetic waves travel in a vacuum at the same speed, regardless of their frequency. The magnitude of their velocity is

$c=3\cdot 10^8 m/s$

This value is one of the universal constant and it is called speed of light.

According to Einstein's theory of special relativity, the value of c is the same for all inertial frames (it means that we measure always the same value of c in a vacuum, even if we are moving with respect to the light).

However, the speed of the electromagnetic waves decreases as they move through a medium. In particular, their speed decreases according to the equation:

$v=\frac{c}{n}$

where n is called index of refraction of the medium.