Question

Two capillaries of same length and radii in the ratio 1 : 2 are connected in series. A liquid flows through them in a stream lined condition if the pressure across the two extreme ends of the combination is 1 m of water, find the pressure difference across first capillary.

Answer 1

Here, \(\frac{πP_1r^4}{8ηl}=\frac{πP_1(2r)^4}{8ηl}\) 

i.e., P₁ = 16P₂

Given that P₁ + P₂ = 1 m

P₁ + \(\frac{P_1}{16}\) = 1

or P₁ = \(\frac{16}{17}\) = 0.94 m