The wave described by $y=0.25 \sin (10 \pi x-2 \pi t)$, where $\mathrm{x}$ and $\mathrm{y}$ are in meters…

The wave described by $y=0.25 \sin (10 \pi x-2 \pi t)$, where $\mathrm{x}$ and $\mathrm{y}$ are in meters and $\mathrm{t}$ in seconds, is a wave travelling along the
  1. -ve $\mathrm{x}$ direction with amplitude $0.25 \mathrm{~m}$ and wavelength $\lambda=0.2 \mathrm{~m}$
  2. -ve $x$ direction with frequency $1 \mathrm{~Hz}$
  3. +ve $\mathrm{x}$ direction with frequency $\pi \mathrm{Hz}$ and wavelength $\lambda=0.2 \mathrm{~m}$
  4. +ve $\mathrm{x}$ direction with frequency $1 \mathrm{~Hz}$ and wavelength $\lambda=0.2 \mathrm{~m}$

Solution

Give, $y=0.25 \sin (10 \pi x-2 \pi t)$ Comparing with $y=A \sin \left(\frac{2 \pi}{\lambda} \cdot x-2 \pi n t\right)$, we get, $\begin{aligned} & \lambda=0.2 \mathrm{~m} \\ & n=1 \mathrm{~Hz} \end{aligned}$ -ve sign indicates, the $x$ direction. :

Asked in: NEET 2008 (Mains)

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