The figure is a penetration test device. The permeability coefficient of sand I is $k_1=2{10}^{-1}c\frac{m}{s},$ The permeability coefficient of sand $$ is $k_2=1{10}^{-1}c\frac{m}{s},$ The Cross$-$sectional area of soil sample is $200c{m}^2.$ Determine the following:$($a$)$ the height of water head in the piezometric tube at the interface between sand I and sand II$.($b$)$ the unit water seepage at the interface between sand I and sand II$.$

A$2$