The velocity of electromagnetic wave in free space is given by     Select one:dacb

The velocity of electromagnetic waves in free space, commonly denoted as $c$, is a fundamental constant of nature. It is defined as the speed at which light travels in a vacuum. The value of this constant is approximately:

$c = 3 \times 10^8 \text{ m/s}$

This speed is crucial in various areas of physics, including optics, electromagnetism, and relativity. The fact that electromagnetic waves, such as light, travel at this constant speed has significant implications for our understanding of the universe and the behavior of electromagnetic radiation.

In the context of your multiple-choice options (indicated as "Select one: dacb"), the letter representing the correct answer would be the one that indicates this speed, $c$. If "c" is one of the options provided, it would be the correct choice.