Show that if two capillaries if radii `r_(1)and r_(2)` having lenths `l_(1)and l_(2)` respectively are set in series ,the rate of flow Q is given by
`Q=(pip)/(8eta)[(l_(1))/(r_(1)^(4))+(l_(2))/(r_(2)^(4))]^(-1)`
where p is the pressure difference across the arrangement and `eta` is the cofficient of viscosity of the liquid.