Question

Which of the following waves is progressing in the $y$ direction ?

• A. $x=x_0\cos (\omega t-ky)$
• B. $y=y_0\cos (\omega t-kx)$
• C. $y=y_0\cos kx\sin \omega t$
• D. $y=y_0\sin kx\cos \omega t$

Answer 1

The correct option is A $x=x_0\cos (\omega t-ky)$

Equation (a) : $x=x_0\cos (\omega t-ky)$ represents a wave travelling along $y$ direction.

In contrast, equation (b) is for a wave travelling in $x$ direction while equations in options (c) and (d) represent standing waves.

Hence, option (a) is correct.