(b) Given, $y = y_{0}\sin{2\pi\left( ft - \frac{x}{\lambda} \right)}$ For particle velocity, $\left( \frac{dy}{dt} \right)_{\max\ } = 2\pi fy_{o}$ Wave velocity =$f$λ Accordingly, $2\pi fy_{o} = 4(f\lambda)$ Or $\lambda = \frac{\pi y_{0}}{2}$
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