Answer in Physics for Pushpo #163294
Discuss the phase velocity and group velocity in details with net diagram.
In order to convey information, something more than a simple harmonic wave is needed. However, the superposition of many such waves of varying frequencies can result in an “envelope” wave and a carrier wave within the envelope. The envelope can transmit data. A simple example is the superposition of two harmonic waves with frequencies that are very close (w1 ~ w2) and of the same amplitude.
The envelope (the green line) is given by u1 and travels at the group velocity. The carrier wave (the blue line) travels at the phase velocity and is given by u2. The wave packet moves at the group velocity. It is the envelope which carries information. Group velocity and phase velocity are not necessarily the same.