Given that   $y=A\sin \left(\frac{2\pi }{\lambda }(ct-x)\right)$  where x and y are measured in metres. Which of the following statement is true?

Here,  $y=A\sin \left(\frac{2\pi }{\lambda }(ct-x)\right)$

where, x and y are measured in metres. 

A is amplitude of wave, whose unit is metre and x is also in metre (given)

$\therefore$ Unit of  $\lambda$ is same as that of x and A, i.e. metre.

However, unit of c (speed of light wave) is ms^-1 which is not same as the unit of $2\pi /\lambda$, i.e. metre^-1.

 Similarly, unit of (ct $-$ x) is metre which is not same as the unit of $2\pi /\lambda$.