A wave travelling along the x-axis is described by the equation $y(x,t)=0.005\cos (\alpha x-\beta t)$ . If the wavelength and the time period of the wave are 0.08 m and 2.0 s, respectively, then $\frac{\alpha }{\beta }=n\times 5$ then the value of n is (where $\alpha ,\beta$ are in appropriate units).