In Young’s double slit experiment the two slits act as coherent sources of equal amplitude $A[{\text{I}}_0=5{\text{\hspace{0.17em}\hspace{0.17em}W/m}}^2]$  and wavelength $\lambda$ . In another experiment with the same set-up the two slits are source of equal amplitude  $A$ and wavelength $\lambda$ , but are incoherent. The difference of the intensity of light at the midpoint of the screen in the first case to that in second case is ____${\text{W/m}}^2$ .