Question

$y = a\cos(kx + \omega t)$ superimposes on another wave giving a stationary wave having node at x = 0. What is the equation of the other wave

• A. $- a\cos(kx + \omega t)$
• B. $a\cos(kx - \omega t)$
• C. $- a\cos(kx - \omega t)$
• D. $- a\sin(kx + \omega t)$

Answer 1

Answer: (C)

$- a\cos(kx - \omega t)$

Answer 2

$a\cos(kx + \omega t)$

hence $y_{\text{reflected}} = a\cos( - kx + \omega t + \pi) = - a\cos(kx - \omega t)$