Question

Two capillaries of same length and radius in the ratio of 1:2 are connected in series and a liquid flows through this system under streamline conditions . If the pressure across the two extreme ends of combination is 1m of water, what is the pressure difference across the (i) first capillary (ii) second capillary?

Answer 1

`V = (pi p_(1)r^(4))/(8 eta l) = (pi p_(2)(2r)^(4))/(8 eta l) or p_(1) = 16 p_(2)`
But , `P_(1)+p_(2) = 1 `
so `p_(1)+(p_1)/(16) = 1 or p_(1) = 16/17 m`
and `P_(2) = 1 - p_(1) = 1- 16/17 = 1/17 m`.