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Q.
The equation $y=a \sin \frac{2 \pi}{\lambda}(v t-x)$ is expression for
Waves
Solution:
The equation of progressive wave propagating in the positive direction of $X$-axis is
$y=a \sin \frac{2 \pi}{\lambda}(v t-x) $ or
$y=a \sin (\omega t-k x)$