Howtosignalprocessing
In vacuum, phase and group velocity (defined for plane waves) are identical at c = 299 792 458 m/s. Within the International System of Units (SI), the vacuum velocity of light has been defined to match this value exactly.
- What do you mean by phase velocity?
- What is phase velocity and its formula?
- Why phase velocity is faster than speed of light?
What do you mean by phase velocity?
The phase velocity is defined as the velocity for a single-wavelength wave, whereas the group velocity is defined as the velocity for a packet of waves in which the waves vary in wavelength.
What is phase velocity and its formula?
A plane wave traveling in the + z direction can be written as sin k z − ω t . The wave moves at a speed that keeps the argument of the sine function a constant. For convenience, this constant is chosen to be zero and the argument becomes k z − ω t = 0 . Rearranging this equation gives z / t = ω / k .
Why phase velocity is faster than speed of light?
Since the phase velocity is = lambda x f and f is the same then the guided phase velocity is greater than the free space wave velocity C, the speed of light.
