any fixed instant) as a function of x is a sine wave. Similarly, take a fixed location, say x = x . Then, the argument of the sine function in Equation ( . ) is constant - ω t .
The displacement y , at a fixed location, thus, varies sinusoidally with time. That is, the constituents of the medium at different positions execute simple harmonic motion. Finally, as t increases, x must increase in the positive direction to keep kx – ω t + φ constant. Thus, Eq.
( . ) represents a sinusiodal (harmonic) wave travelling along the positive direction of the x -axis. On the other hand, a function