Q 1 :    

The displacement of a travelling wave $y=C\sin \frac{{\displaystyle 2\pi }}{{\displaystyle \lambda }}(at-x)$ where $t$ is time, $x$ is distance and $\lambda$ is the wavelength, all in S.I. units. Then frequency of the wave is     [2024]

• $\frac{2\pi \lambda }{a}$

   

• $\frac{2\pi a}{\lambda }$

   

• $\frac{\lambda }{a}$

   

• $\frac{a}{\lambda }$